Ellet was primarily known as a suspension bridge builder, but, he was prominent in early work on canals and railroads and later made major contributions to river management, economic analysis of transportation modes and ramboats. He was born in Penn's Manor, Pennsylvania on January 1, 1810. As a boy in 1827, he went to work as an assistant on surveys for the Susquehanna River under [Canvass White] and later on the Chesapeake & Ohio Canal under [Benjamin Wright]. In 1830 he decided to visit Europe to study engineering at the Ecole des Ponts et Chaussees in Paris, France. He became a believer in the use of wire suspension bridges as built by the Sequin brothers over rivers in France.
After returning to the United States in the summer of 1832, he proposed a mile long series of suspension bridges to cross the Potomac to replace the Long Bridge built in 1808. He was ahead of his time, and government leaders were reluctant to award a major project to a very young and inexperienced civil engineer. He then went to work for Wright doing surveys of the New York and Erie Railroad. In 1835 he followed Wright to the James River and Kanawaha Canal in Virginia. When Wright left the company he became the Chief Engineer for four years.
In 1838 Lewis Wernwag's Colossus Bridge over the Schuylkill River near Philadelphia was burned by an arsonist. At the time its 340 foot main span was the longest single span bridge in the United States. Ellet immediately proposed replacing it with a wire suspension bridge. In 1839 he wrote "A Popular Notice of Wire Suspension Bridges," a 12-page pamphlet that was later reprinted in the American Railroad Journal in order to promote his proposal. He noted "If the breadth of the stream be not over the third of a mile, and the project is sufficient to justify the cost, a bridge may be constructed without the need of pier in the channel...As a contribution to the architecture of the city and as an ornament to the Schuylkill it would be unsurpassed..." [Fairmount Bridge over the Schuylkill River] His design for a central span of 357 feet was selected from over five competing designs. He wrote that his drawings appeared to some "more like cobweb or gossamer than the rough stuff adapted to the wear and tear of heavy teams and droves of beef cattle..." The county did not have the resources to build it for another two years.
Before construction started, he proposed a bridge in St. Louis across the much wider Mississippi River. He presented his 59-page report with drawings on January 1, 1840. It was a remarkable report and gave details of the proposed bridge. His estimated cost of $737,566 was beyond the city's ability to finance at the time. A bridge was not placed at the site until 1874 when James Eads built his three-span steel arch structure. Ellet returned to Philadelphia and built his Schuylkill River Bridge. Progress on the bridge was kept in front of the profession by another article in the American Railroad Journal . The editor noted "if Mr. Ellet succeeds in accomplishing the work at his estimate, we speak for this sort of bridge, a degree popularity which may eventually remunerate him for the hardness of his present bargain." The bridge opened in the spring of 1842 with a final cost of $53,000. He visited Niagara Falls in 1833 to survey a site for one of his suspension bridges, but his next visit wasn't until 1845 when he heard there was renewed interest in building a bridge across the gorge for railroad and carriage traffic. In 1847 a new Ellet proposal was accepted, with modifications. The span was 800 feet with a deck width of 28 feet for two carriageways, two footways and one railway track in the center of the floor. He was also selected at the same time to build a bridge across the Ohio River at Wheeling. His first proposal for a bridge at the Wheeling site had been submitted in 1836 followed by another in 1841 and still another in 1847 that was for a bridge with a main span of 1,010 feet. The bridge opened November 15, 1849 and was the longest span bridge in the world at the time serving well until May 14, 1854 when it blew down in a severe windstorm. Ellet rebuilt it, using existing cables, etc. to a single lane bridge shortly after. Later the bridge was rebuilt by his associate Captain McComas in 1860 and then by Washington Roebling in 1872. It still carries traffic across the river.
After the Wheeling Bridge opened, he devoted full time to building a preliminary bridge across the Niagara. Ellet charged people toll monies to use his preliminary bridge while he was constructing the final bridge. A legal battle over who should retain these monies took place over the next six months. The issue was settled with Ellet receiving $10,000 for monies owed to him and his contract terminated. John A. Roebling was then awarded the contract in 1851, and his bridge opened in 1855 as a double deck bridge with the railroad on the top deck and carriageways and sidewalks on the lower deck. Near the end of construction on his Wheeling Bridge he submitted a proposal for a railway suspension bridge to cross the Connecticut River at Middletown, Connecticut. In his 1848 report he proposed a 1,050 foot bridge between towers with the deck approximately 140 feet above low water. No action was taken on his proposal. He prepared a design for a bridge for carriages and pedestrians across the Ohio River at Cincinnati in 1849. It had a central span of 1,400 feet and provided a shipping clearance of 112 feet. He later proposed a 1,000 foot railroad and carriageway bridge across the Potomac River near Georgetown. This was his last bridge proposal and his last involvement with bridge building. He spent most of the rest of the 1850s making plans to control flooding and enhance navigation on the western rivers.
During the Civil War, he proposed the construction of ramboats to clear Confederate gunboats from the Mississippi River. He was later given the rank of Colonel and built nine ramboats. He led them in the Battle of Memphis where his boats were instrumental in the victory. Unfortunately, Ellet was struck in the knee by a sharpshooter's bullet resulting in his death June 21, 1862. Gene Lewis, Ellet's biographer, wrote that he should have been recognized as "a true genius. He had an inordinate amount of imagination, originality, and creativity..." He, more than John A. Roebling, introduced the long span wire suspension bridge to the United States with his Fairmount, Niagara and Wheeling bridges and his many articles and reports between 1832 and 1852. On all bridges where there was direct competition, Ellet was selected over Roebling, indicating that at least in the 1840s Ellet was, in the eyes of bridge promoters, the leading suspension bridge engineer in the country.