The Steamboating Era
The need for a railroad in Cairo, Illinois was great by the late 1800s.(1) As many as 500,000 railroad cars were ferried across the Mississippi and Ohio River each year, and by 1886, shipments via the river and railroad were valued at $60 million, the highest per capita in the nation.(2) The Illinois Central (IC), incorporated in 1851, extended from Galena in the northwestern part of the state to the southernmost tip, Cairo, and connected major agricultural and industrial centers, with a branch serving Chicago. At the time of its completion, the IC was the lognest single railroad operating in the United States at 700 miles in length.(3)(4)(5) At its southern terminus, the IC connected to the two rivers, taking advantage of the burgeoning steamboat traffic along the Ohio and Mississippi.
A discussion for a bridge across the Ohio River first came on January 1, 1859, when IC Master of Transportation James C. Clarke, who later served as president of the railroad, stated that the railroad’s natural connections were with the railroads leading to Mobile and New Orleans, and that a completion of a line south by August of 1860 would reap great benefit.(3)(6) The growing importance of trade along the Gulf was a major factor in the initial push. Senator Stephen A. Douglas supported the Lakes-to-Gulf railroad route, as it was named, as did IC President William H. Osborne, who predicted that his company, with its connection to the Mobile and Ohio Railroad, would provide “a great avenue of commerce” to the cities along the Gulf.(7)
But the “Great River,” so aptly named by the Seneca Indians, proved to be a major obstacle as the river was found to be very wide at that point.(3)(8)
The Ohio River Bridges Bill
During this time, the Mississippi and Ohio Railroad (M&O) extended its railroad north to Columbus, Kentucky, just shy of Cairo by about 20 miles. A connection between the M&O and the IC was made via a steamboat along the Mississippi, but just days after the connection was made, Fort Sumpter was attacked and delayed any further work between the two companies.(3) In 1870, during the midst of Reconstruction, the IC attempted to persuade the M&O to extend its railroad north towards Wickliffe, with the IC President, John Douglas, even offering the cash-strapped M&O funding for the extension. But because of M&O’s precarious financial situation, due to the railroad having to rebuild its lines in the south, the IC began to seek another route to the south.(3)(9)
In 1872, the IC negotiated with the Southern Railroad Association to extend the Mississippi Central (MC), which later became the Chicago, St. Louis and New Orleans (CSL&NO), to Wickliffe opposite to Cairo. Both railroads felt that there was no immediate need for a bridge, given that the IC used standard gauge and the MC used a five-foot gauge, and that much expense would need to be undertaken to correct the gauge. To transfer goods across the river, the IC commissioned a steam transfer ferry, the H.S. McComb, in 1873, which could carry six passenger cars or twelve freight cars, and the first run across the Ohio River was on December 24. A slightly smaller steamer, the ten-car W.H. Osborne, was later added to the fleet.(3)(10)(11)
But competition was fierce, as other railroads began to build out their bridges across the Ohio River from Steubenville to Cincinnati. Traffic was beginning to shift to other railroads, and the IC saw the need for a fixed crossing ever the more warranted. But steamboat operators saw the move as an attack on their industry, going as far as to claim that the bridge piers would be hazards to river navigation and that its low height would hinder their vehicles. But that point was mostly exaggerated, and was backed by earlier Congressional decisions as a result of the completion of Wheeling Bridge in Wheeling, West Virginia.(12)(13)
But the passage of the Ohio River Bridges Act in 1872, heralded as a victory by steamboat operators, required more extensive planning, map, and profiles be developed for a crossing over the Ohio River than any other navigable waterway.(3)(14) The Act specified that 40 to 45 foot minimum high-water clearance heights, 350-foot channel span lengths and pivot spans for tall-stacked boats be required. In addition, the railroad or bridge company had to notify the Secretary of War of its intensions, and to present documentation on the bridge’s design. The Secretary then had to appoint a board to review the plans, and upon their approval, enter into a contract with the proposing company.(14) Other rivers, such as the Missouri and Mississippi, were granted charters individually by Congress, although the design guidelines were enforced on a policy level by the War Department. As a result, a black market for bridge charters developed, with one Mississippi River bridge charter fetching $250,000. The law was in effect until 1883.(14)
An 1883 amendment to the Ohio River Bridges Bill from 1872 allowed for the removal of a pivot span if a 53-foot high water clearance was provided.(30)
In July 1881, the MC changed the entire 550-mile length of their railroad from Ballard County opposite of Cairo to New Orleans to standard gauge, an operation that took less than one day but required 3,000 laborers.(16)
A Push for a Bridge
The first push for a bridge post-Civil War came from Judge Lawrence S. Trimble of Paducah, Kentucky, who was president of the New Orleans and Ohio Railroad (NO&O). Trimble had proposed a span for the IC in the mid-1870s, and had hoped that a bridge at Paducah would allow a connection of his NO&O to the IC and allow his city to prosper over Cairo. The plan was not well received by the IC.(15)
Another effort in 1870 by the IC President W.K. Ackerman ordered preliminary surveys made of an Ohio River bridge, and officials at the IC and the CSL&NO spent the next few years surveying for a bridge site.(16) By 1884, the IC was transferring 52,000 freight cars and 8,000 passenger cars a year at Cairo by steamboat, and a bridge was desperately needed.
On March 17, 1886, the Commonwealth of Kentucky authorized both the IC and the CSL&NO to build a bridge over the Ohio River at Cairo, since Kentucky’s state line extended to the low water line on the Illinois shore. An amendment by the Kentucky legislature, at the request by those wanting a railroad span at Paducah, provided for a bridge at either Cairo or any point within five miles of the city limits of Cairo or Paducah.(17) The railroad companies even briefly considered tunneling under the Ohio River to avoid opposition from steamboat interests, although this was soon rejected as cost prohibitive.(18)
Edward T. Jeffrey, general manager of the IC, was named general manager of the CSL&NO to supervise the bridge construction.(19) Jeffery asked Morison and E.L. Corthell to review a design of the bridge prepared by another engineer, and Morison and Corthell issued a joint report in February 1887 that made general comments about the superstructure and substructure, but noted that a site inspection with Jeffrey was needed. On March 11, Morrison, Corthell, Jeffery and George Field of the Union Bridge Company met at the proposed bridge site during a spring flood of the Ohio River, which allowed them to witness the impact of the waters on the topography and helped formulate early bridge design guidelines. Borings were made about 200 feet beneath the river, which revealed that it was nothing more than sand and gravel. In a report to Jeffrey, Morison and Corthell recommended that hybrid piers be designed, constructed with pneumatic caissons to provide additional stability. It was recommended that the foundation consist of timber crib-work filled with concrete.(20)
The proposed bridge site featured a river width of 4,000 feet. Two miles upriver, the width narrowed to around 3,000 feet, which raised the possibility of filling in with stone some of the shoreline to narrow the channel.(20) But that idea was rejected, leading Morison and Corthell to design a 52 truss steel span bridge with a length of 10,560 feet, the longest of any metal bridge in the world.(21)(22) The total length, including trestles, was 20,461 feet, or a whopping 3.875 miles. The channel portion of the crossing consisted of nine pin-connected, Whipple through truss spans, two of which were 518.5 feet long and the other seven 400 feet long, and three 249 foot Pratt deck spans. The pin-connected Whipple trusses were also 18 inches longer than the 1877 Cincinnati Southern bridge as well. But the lengths of the Whipple trusses double panel diagonals led to less rigidity under load. Morison had proposed extremely long truss spans for other bridge sites previously, but conservative railroad clients had nixed all of those ideas until now. The length also included 9,901-feet of timber trestle.(39)
The proposed bridge would be far heavier than any bridge that Morison had engineered. The steel for the twelve spans weighed 13.5 million pounds, and the approach ramps weighed an additional 7.8 million pounds. Counting for the superstructure and substructure, but not the approaches, the Cairo span weighed 194.6 million pounds.(25)(26) For comparison, the Nebraska City Bridge superstructure that Morrison had also designed weighed a measly 3 million pounds.(23)(24)
Each of the Whipple through trusses and deck truss approach spans would be supported with masonry piers, some of which would weigh 9,400 tons. Each of the 518-foot channel trusses would also be subdivided into 17 30-foot panels with a width of 28 feet and a height of 63 feet.(27) The Kentucky approach included 21 deck spans, each 150-foot long, and one 106-foot span.(28) The Illinois approach included 17 150-foot deck spans and one 106-foot span. Each would be supported by cylinder piers filled with concrete, with the trestles constructed entirely of steel. The substructure for the channel spans consisted of ten massive masonry piers founded on pneumatic caissons, the deepest of which were to be extended 75 feet below the low water level. That would make the total height of the bridge, from the bottom of the foundation to the top of the bridge, 250 feet. The caissons would be 70 feet long, 30 feet wide and 18 feet high.(29)
The piers consisted of limestone quarried from Bedford, Indiana, with F.H. Joyner overseeing the excavation and construction. Morison, however, specified granite for the upstream nosing stones from the starling copings to the low water marks of the piers.(29)
The contract with the War Department stipulated that work on the Cairo crossing be started before March 29, 1887, and pile driving for the Kentucky approach had already commenced when Morison began preparing construction plans for the main spans. Morison acted as chief engineer, and Corthell as associate chief engineer, and Morison recommended that the IC employ the Union Bridge Company to construct the substructure and superstructure.(14)(20) The contract was awarded in May to Union for the superstructure.(31)
On July 1, 1887, workers began framing for the first caisson, Pier XI. The iron workers set the 67-ton cutting edge for the pier on the launching ways on the Cairo shore ten days later, and on July 21, the workers began building the heavy timber. By mid-August, they had launched the completed caisson into the Ohio River and maneuvered it into position, where it was pressurized and sunk to the river bottom. A pumping crew operated pneumatic equipment from a barge over the caisson and sand hogs in the pressurized chamber began excavating through the bed of the river at a rate of four inches per day. On October 6, the crew completed the timber crib on the caisson roof and the laying of granite and limestone blocks began five days later.(32) By November 10, the caisson floor reached nearly 75 feet below the low water mark of the Ohio.
There were some issues of caisson fever due to the air pressure that reached 35 PSI at such depths within the river. Some workers were temporarily paralyzed and two were killed as a result. Hot coffee and baths, with cool air being pumped down into the chambers, seemed to solve the caisson fever issues at first, although five other workers died.(33)(34) A second pneumatic crew was later added, loaded on the steamboat Kate Elliott. The masons set the last stone on the coping of Pier VIII on February 19, 1889, completing the piers for the Cairo bridge.(35)
Steelworkers from the Baird Brothers began constructing the superstructure in July 1888, taking in prefabricated truss components that was being shipped via rail from the Union Bridge Company in Pennsylvania. The workers erected a pile falsework and traditional timber traveler. A team of twelve handled the steel incoming from the train, who directed it to a derrick that lifted the components to a ten-ton push cart. A second twelve person crew pushed the material to the large timber traveler. A team of 25 would then assemble each channel span, with eight on top of the scaffold of the traveler, two at the ropes, two at the engine, and one engineer who supervised,(27) taking only six days to complete one span. The falsework would be removed and used again for the next span to be built.
By the end of August 1889, the steelwroerks from Baird had completed the last through truss.(27)
Shortly after 9 AM on October 29, the first train crossed the bridge from Illinois into Kentucky. Thousands traveled to Cairo via aboard chartered trains to catch a glimpse of the bridge. The first test train consisted of nine 2-6-0 Mogul locomotives that weighed 75 tons each and were the heaviest IC engines in service. Engineer Gordon Weldon was on hand, along with IC President Stuyvesant Fish and Vice President E.H. Harriman. In the engine prior was M. Eagan as engineer, and IC General Manager C.A. Beck and General Superintendent A.W. Sullivan. The 675-ton train inched across the Cairo bridge, and when the last engine passed the easternmost truss, mass pandemonium broke out in the crowds of Cairo. The first train then backed over the bridge and picked up a tenth Mogul engine and sped across the bridge at full speed, followed by a second train full of newspapermen. A southbound freight followed right after, which inaugurated regular service over the new bridge.(36)(38)
Work still remained on the bridge, which included construction on the floor, painting and other minor details that continued until March 1, 1890. The total cost broken down:
- Substructure: $1,189,743.73
- Superstructure: $765,616.14
- Illinois approach: $338,267.40
- Kentucky approach: $290,190.51
- Protection works: $8,622.87
- Service tracks: $565.90
- Right-of-way/franchises: $12,277.63
- Engineering: $67,620.65
- Legal/supervisory: $947.24
- Miscellaneous: $1,605.85
- Total: $2,675,457.92 
The bridge was just slightly more than $200,000 over the original estimate.(37) The crossing, at 10,560-feet, was the longest steel bridge in the world.(38)
- Type: Through truss, deck truss
- Largest span length: 518.5 feet
- Total length: 20,461 feet including wooden approach trestles; 10,580 feet
- Height above high water: 53 feet
In 1891, the 9,901-foot timber trestle was replaced with fill.(39) On October 31, 1895, a 6.6 earthquake on the New Madrid Sesmic Zone cracked a pier on the bridge.(2) Repairs were completed immediately afterwards.
In 1914, the original floor system of the truss spans were reinforced, and the floor system of the approaches were replaced in 1934 and 1935.(38)
In 1921, plans were submitted to the War Department for the replacement of the Cairo Bridge with a double track superstructure, reusing the existing piers.(38) Opposition to that plan ultimately killed the double tracking idea. In 1932, a supplementary freight line for the IC was completed from Edgewood south to Reevesville, connecting to an existing IC line from St. Louis that utilized the existing Metropolis, Illinois-Paducah, Kentucky Bridge. The secondary line connected to the IC at Fulton, Kentucky.
On May 25, 1946, the IC requested Modjeski and Masters to complete a study of the current condition of the Cairo Bridge.(38) In the report, the company stated that the reinforcements to the bridge in 1914 and in the 1930s increased the dead load carried by the spans and that there were a number of points on all of the spans were the pins had been worn out. As a result, the distribution of stresses were hammered along the bars of the end hanger members - where one bar, for instance, carried 97% of the total live load stress due to pin wear of an outer eyebar.
The expansion rollers had also been worn to an elliptical shape, and the shoes had developed pockets into which the rollers fitted that resisted expansion movements. As a result, some cracks were formed in the stone masonry of the piers that required steel banding.(38) The report also stated that the Whipple trusses under live loads were overstressing the bottom chords by 30% and 45% of the 518.6-foot and 400-foot spans, and that there were varying amounts of overstresses in the top chords and end posts, and bottom laterals under high wind.
The report recommended that the live loads and speeds not increase on the Cairo Bridge, and that the existing crossing be replaced as it had reached the end of its useful life.(38) To keep the bridge in service, an anemometer was installed so that when high winds were reported, trains would be prohibited from the bridge.
Plans to replace the bridge began in July 1947 under Modjeski and Masters.(38) Early studies focused on constructing a bridge 150-feet upstream from the existing bridge and using some of the existing approaches, given that there were concerns with high water and drift hazards that a temporary bridge could encounter during the reconstruction process. During the development process, consideration was given to a channel span of 648-feet, the same as the Louisville & Nashville (L&N) Bridge at Henderson, Kentucky, but to give a good arrangement of trusses on the new bridge, the channel span length was increased to 688-feet, with a navigation clearance of 668-feet, or 20-feet more than the L&N Bridge.
After discussing the options with the Army Corps of Engineers, a revised plan was developed for a new bridge 150-feet upstream, with the main channel closer to the Illinois shore, with a main cantilever span for the channel with a 721-foot length. Piers IX through V would remain in place, with new piers C through G being replaced. On the Kentucky approach, 255-foot deck spans would be constructed to replace three existing 405-foot through spans. A formal report was submitted to the War Department in July 1947 for approval.(38)
A public hearing was held on August 26, and opposition developed among river boat interests who called for a longer clear navigation. The IC Metropolis Bridge was 700-foot, and the Cairo Highway Bridge was 800-foot.(38) The desired length was 800-feet. Instead, the IC submitted an application for reconstruction of the existing bridge on the existing alignment, which was approved by the Chief of Engineers and the Assistant Secretary of the Army on July 6, 1948 with a condition that at least two of the four spans on the Illinois shore be kept free of falsework at all times.
Because of the poor conditions of some piers, a concrete jacket would be needed around Piers X, VIII and VI to stabilize them for the long term.(38) An encasement, two feet thick, was designed to be attached with expansion anchors to alternate stone courses by a pattern of anchors.(39)
In early 1948, Modjeski and Masters were requested by the IC to prepare plans and specifications for the reconstruction of the Cairo Bridge. The new design incorporated all riveted through truss spans of the same lengths as the original bridges, except for the 1,215-foot section over the Kentucky bank where three 405-foot through trusses would be replaced with six 200-foot deck trusses.(38) Specifically, the superstructure consisted of two 518.11-foot and four 400.11-foot Warren Through truss spans, and six 197.7-foot deck truss spans.(39) The widths would vary, 25-feet for the 518-foot spans, and 22-feet for the 400-foot spans. The new construction involved 3,884.675-feet.
The design called for carbon steel to be used in the trusses, except for the chords and some diagonals of the 518-foot spans, where silicon steel proved to be more economical. To guard against brine drip, all bottom laterals, top cover plates of stringers and floor beams, plates and top angles of the stringer cross frames of the through spans called for copper bearing steel.(39) All truss bearings were to be on stainless steel rollers, 10 inches in diameter, geared to similar alloy metal roller plates.
The contractor submitting a bid was required to do the work of constructing the new spans and shifting the spans in a manner as to meet the navigation requirements set forth by the Department of the Army. Because of the high cost of detouring all freight to the Metropolis Bridge, the bidding contractors were required to state as an item of their bid the number of hours of detour time which was evaluated at one-half the estimated cost of detouring trains. An equal penalty was provided for exceeding the time in the bid.(38)
Contract to conduct soil borings used for the reconstruction design that were taken in 1947 were award to Sprague and Henwood, Inc. on June 11.(40) The contract called for borings at 15 points, and the first hole was drilled just four days later. The work was completed on October 8.
An investigation of the masonry piers began on September 7, 1948 when a contract was awarded to the Pennsylvania Drilling Company.(40) The company conducted core drilling of two holes completely through Piers VI, VIII and X to examine the stone and mortar. Drilling began on September 17 at Pier VIII and was completed on October 20 at Pier X. The drilling process was without mishap and the results showed that the core of the piers were 90% to 100% in terms of condition. A visual inspection indicated excellent bond between the stone and mortar.
During this time, representatives of the Illinois Central Railroad conducted preliminary surveys of clearance requirements, pier top masonry and alignment, span lengths and soundings around all of the piers. Elevations and span lengths were rechecked from February 3 to 16, 1949.
The scope of the work involved in Substructure Contract No. 1 was to complete changes and additions to the substructure of the existing bridge to adapt it to the new superstructure.(40) This involved the encasement of Piers VI, VIII and X with reinforced concrete anchored to the existing stone and supported on tremie seal supplemental footings, which were to be supported by steel bearing piles. It also involved cutting recesses in Piers II to V for the bearings of the new deck truss spans, and the construction of three new reinforced concrete piers at the midpoints of each of the through spans between Piers II and V for the new deck trusses. Bids for this contract were received on May 4, 1949 and on May 21, the contract was awarded to the Kansas City Bridge Company and the Massman Construction Company, who had bid jointly. The contractor began shipping in equipment in early June and construction began on July 19. The contract required that the work be completed for the superstructure construction within one year and that all work on the pier be finished 150 days after that.
The first concrete pour for this contract was made at Pier C on November 2.(40) The initial process involved batching the three mixer trucks at a ready-mix plant that was located about 1/4-mile north of the north end of the bridge, then hauling the trucks to the top of the levee, back down the trestle where the concrete would be dumped into a hopper, and from the hopper into 1.0 cubic yard buckets on a pontoon which would be transported across the river via a tugboat. The concrete would then be transferred via a pumpcrete machine by crane to the vicinity of Pier C. This was a very slow process, and only 10.5 cubic yards of concrete were poured per hour.
To speed things up, a narrow, 3-foot gauge railroad was built from the Kentucky bank to Pier C and employed one engine and two flat cars in the spring of 1950.(40) A 6.0 cubic yard hopper was set up over the river end of the railroad so that the concrete could be dumped by gravy into the three 1.0 cubic yard buckets that were discharged into the forms by a crawler crane. The pours were faster, at 25 to 30 cubic yards per hour.
- Excavation around Pier X for pier encasement began August 16, 1949.(40) Soon after, expansion anchors were drilled and placed in the pier from top down to the water line, followed by the driving of steel bearing piles for the new reinforced concrete jacket. But due to flooding in 1950, work was slowed although it was finished on October 5.
- The encasement of Pier VIII began on October 6, 1949 and was completed on February 21, 1951.
- The encasement of Pier VI began on July 19, 1949 and was finished on January 17, 1951.
- Construction of a new caisson pier, midway between existing Piers IV and V, began on October 13, 1949 and was completed on March 23, 1951.
- Work on Pier B, between Piers III and IV, began on September 21, 1949 and was finished on March 22, 1951.
- The excavation for Pier C, located between Piers II and III, began on September 13, 1949 and construction was completed on March 22, 1951.
- The completion of the recesses in Piers II and V, which were the most difficult part of the construction of Contract No. 1, were hampered by high water and the small size of the openings. While the work was slow, it was all but completed on March 21, 1951.
The scope of the work for Superstructure Contract No. 2 was to replace nine through trusses, six Warren through trusses and six deck trusses.(40) The contract specified that the bridge would continue to operate through the reconstruction of the superstructure, with a bonus and penalty of $200 per hour for time either saved or lost compared with a total number of hours of anticipated detour time that each contractor would provide. Bids for the superstructure were received on September 1, 1949 with the American Bridge Company being awarded the contract with a detour time of 292 hours listed in their proposal.
The contract specified that the American Bridge Company was limited to the erection of the spans on falsework adjacent to their final position, which would then be rolled into place.(40) To facilitate quicker construction, two of the 200-foot deck truss spans for the Kentucky bank were adapted to provide falsework for the river spans. The trusses were slightly strengthened and a few members were added to extend the spans for full-length falsework. Two short spans were supported at each pier by a steel bent resting partly on the pier and partly on a steel pile foundation, and at midpoint by a common steel bent supported by a steel pile foundation. They could then be moved by picking up the components and moving them via a barge.
The contractor began assembling crews and equipment on April 24, 1950, and preliminary work involved the construction of a field office and the preparation of barges for derricks and for mounting structural towers for moving falsework spans.(40) Falsework bents were built for Span 10, and two falsework deck spans were completed. Preparations for erection work were finished on September 2.
Due to the complexities of the requirements as to the maintenance of river and rail traffic, the contractors developed a scheme of erecting the new truss and the disposal of the old span, which involved the rection of a span on falsework complete with track, the rolling out the old span onto falsework, the rolling in the new span, and the launching and salvaging of the old span.(40) The old spans were rolled out and set down on temporary end supporting framework (sled) on the upstream side of the bridge, and were launched into the Ohio River. It was a method that was far cheaper than dismantling the span component by component.
The 200-foot deck spans on the Kentucky bank were erected near their final position and were rolled in.(40) The falsework consisted of steel bents that were kept to a minimum by trussing up the bottom chords with wire ropes in four-panel lengths for the initial stage, and then after the web members and top chords were filled in, by cantilevering the remaining four panels. The two 200-foot deck spans replaced one 400-foot through span, and were rolled together into place.
Contract No. 2 work was completed in May 1952 (38) with only 119 hours and 45 minutes of detour time, much shorter than the 292 that the company had requested.(40) The shortened time was attributed to the launching of the trusses.
- Span 10 was launched on November 9, 1950 and the span was opened to navigation on June 11, 1951. The salvage of the old span was delayed by high water.
- Span 9 was launched on June 27, 1951 and the span was opened to navigation on August 11.
- Span 8 was launched on August 21 and the span was opened to navigation on September 15.
- Span 7 was launched on September 27 and the span was opened to navigation on October 16.
- Span 6 was launched on November 1 and the span was opened to navigation on March 24, 1952.
- Span 5 was launched on December 31, 1951 and the span was opened to navigation on March 24, 1952.
- Type: Warren Through truss
- Largest span length: 518.11 feet
- Total length:
- Width: 22-25 feet
- Height above high water:
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- “First Half Century.” The Cairo Project. Southern Illinois University Carbondale School of Journalism, n.d. Web. 9 Feb. 2012. Article.
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- Plowden, David. Bridges: The Spans of North America. Norton, 2001. 75-78. Print.
- “An Act to Authorize the Construction of Bridges Across the Ohio River, and to Prescribe the Dimensions of the Same.” 17 Dec. 1872. “A General Bill for Western Rivers.” Engineering News, 11 Feb. 1888. Print.
- Corliss, Carlton Jonathan. Main Line of Mid-America. Creative Age Press, 1950. 229-231. Print.
- Fish, Stuyvesant. “Report to the Board of Directors.” From: Stover, John F. History of the Illinois Central Railroad. New York: Macmillan Publishing Co, 1975. 202. Print.
- “An Act Authorizing the Chicago, St. Louis and New Orleans Railroad Company and the Illinois Central Railroad Company, or Either of Them Separately, to Build and Maintain a Railroad Bridge across the Ohio River.” Commonwealth of Kentucky, 30 Mar. 1866. Reprinted in: Morison, George S. The Cairo Bridge. Chicago: Knight, Leonard and Co., 1892. 20. Print.
- Corliss. 229-231.
- Fish. 9.
- Morison, George S. and E.L. Corthell. “Report to E.T. Jeffery.” 3 Mar. 1877. Reprinted in: Morison, George S. The Cairo Bridge. Chicago: Knight, Leonard and Co., 1892. n. pag. Print.
- Morison, George S. The Cairo Bridge. 10. Print.
- “Final Report on the Reconstruction, Illinois Central Railroad, Cairo Bridge Over the Ohio River.” Harrisburg, PA: Modjeski and Masters, 1 June 1953. 15. Print.
- Morison, George S. The Plattsmouth Bridge. New York: S.B. Leverich, 1882. 10. Print.
- Morison, George S. The Nebraska City Bridge. Chicago: Knight, Lenoard and Co., 1892. 14. Print.
- Morison, George S. The Cairo Bridge. 12-13. Print.
- Corthell, E.L. ”Address on Retiring from Presidency of the Western Society of Engineers.” Read before the Western Society of Engineers, 8 Jan. 1890.
- “Fast Erecting on the Cairo Bridge.” Railroad Gazette 11 Jan. 1889. 18-19. Print.
- “The Cairo Bridge.” Railroad and Engineering Journal Dec. 1889. 557.
- Morison, George S. The Cairo Bridge. 10-11. Print.
- “Act of Congress Authorizing Construction of Bridges over the Ohio River.” 17 Dec. 1872. Reprinted: Morison, George S. The Cairo Bridge.
- “Contract for Bridge Across the Ohio River, at Cairo, Ills.” Reprinted: Morison, George S. The Cairo Bridge. 4 May 1887. Note: Contract between the Union Bridge Company and the Chicago, St. Louis and New Orleans Railroad Company.
- Morison, George S. The Cairo Bridge. 11. Print.
- Connor, Edward H. “The Substructure of the Cairo Bridge.” Presented to Engineers’ Club of St. Louis, 19 Feb. 1890. Reprinted: Journal of American Engineering Studies. June 1890. 296-297.
- Morison, George S. The Cairo Bridge. 11-12. Print.
- Morison, George S. The Cairo Bridge. 12. Print.
- Corliss. 226-228.
- Morison, George S. The Cairo Bridge. 14-16. Print.
- Modjeski and Masters. “General Narrative.” Final Report on Reconstruction Illinois Central Railroad Cairo Bridge Over the Ohio River. N.p.: n.p., 1953. 13-21. Print.
- Modjeski and Masters. “Design of Bridge.” 23-28.
- Modjeski and Masters. “Construction of Bridge.” 31-72.