In 1836 a town named New York was platted at the present site of Clinton, but the projected town did not develop. In response to the prospect of a railroad bridge being built across the Mississippi at this point, Clinton was platted in 1855, and its grid developed parallel to the Mississippi River. 8A second, later grid north of First Avenue South bends to the north-northeast to follow the banks of the river. The breadth of the river plain at this location meant that the commercial downtown, the industrial/railroad section, and much of the residential area could be accommodated on flat land. Several railroad projects were launched in the 1850s, and the city was finally connected by the Chicago Northwestern Railroad across the Mississippi to Illinois (the first bridge was completed in 1864) and to Council Bluffs on the Missouri to the west. By the 1870s there were two railroad bridges across the Mississippi, and a rail line extended along the river, first to Lyons and then further north. During that decade Clinton was glowingly portrayed as a thriving city: “Nestling among a young growth of artificial shade trees are many beautiful white cottages and stately brick residences, and towering above them all are noble business blocks that are the result of a rapid and healthy growth.” 9

Clinton's two principal industries throughout the latter part of the nineteenth century were lumbering and the railroad. To this was added the economic advantage of the city's having acquired the county seat in 1869. The most influential of Clinton's industries was the Curtis Woodworking Company (founded in 1866), which supplied architectural parts and millwork to the whole of the country and in the process both mirrored and encouraged architectural taste, especially during the years 1910 through 1940. The Curtis Company had its own local impact on the architectural scene by its development of Castle Terrace, a beautifully conceived enclave of period revival houses (1926–1930) set within wooded hills. In the nineteenth century, Curtis's major local competition was the Disbrow Company (founded in 1856) in nearby Lyons. 10This company provided exterior and interior Eastlake, Queen Anne, and early Colonial Revival architectural details to builders all over the state. The lumber industry (primarily sawmills) was so extensive and the companies so successful that Clinton early on had its own contingent of local millionaires, many of whom built substantial houses along South Fifth Avenue and elsewhere. By the mid-1890s, with the depletion of timber, the city experienced a severe depression. Slowly, in the early 1900s, new industry was introduced to the community, but its growth in the remainder of this century has been slow and modest.

In addition to its wide, tree-lined suburban streets, the city developed River View Park, between the railroad and the river's edge, and to the north, Eagle Park. Within the city itself is Mount Pleasant Park (to the west of South Bluff Boulevard at Second Avenue) which from 1883 on was the site for the local Chautauqua meetings. The park contains a number of small cottages, some of which date back to the 1880s.

The city of Lyons, platted north of Clinton in 1877, was annexed in 1895; two years previously, Chancy had been annexed to the southwest. The joining of the two cities of Clinton and Lyons accounts for the second small “downtown” one encounters on Main Avenue, north of Twenty-third Avenue North.