America's Covered Bridges. Ronald G. Knapp

relative numbers of bridges and their ages from the website. The data show a clear pattern of covered bridge building concentrations and document a chronological expansion of the phenomenon. They also provide some indication of how few remain today.

      The old patterns continued. Private companies built turnpike (toll) roads connecting towns and cities as well as into the wilderness, but increasingly the United States Government became involved. In 1811, Congress authorized the building of the “National Road” from Cumberland, Maryland, across West Virginia, Pennsylvania, Ohio, Indiana, and Illinois, terminating at St. Louis, Missouri. By 1818, the road had reached Wheeling, but in 1837, resulting from a “panic,” funding ceased, leaving the road completed only to Vandalia, Illinois. In addition to using Scottish engineer John Loudon McAdam’s technique of constructing roads using pebbles instead of stone blocks or bricks pressed into the soil, the so-called “macadam roads,” designers began to construct handsome stone arch bridges. These included the seemingly mysterious “S Bridges,” mostly in Ohio, so-called because of curves at each end necessary to approach a bridge built perpendicular to the creek. The builders of the National Road, as well as builders of other turnpikes connecting to it, also built covered bridges, with most of them being double lane. Urban bridges also usually had at least one pedestrian sidewalk as part of the bridge. Perhaps the longest crossed part of the Ohio River from Wheeling Island to Bridgeport, Ohio, on the National Road and was a three-span Burr truss structure designed by Lewis Wernwag in 1836. Although nearly burning down in 1883, the bridge survived until 1893 when it was replaced with an iron bridge. Other covered bridges on the National Road and associated turnpikes were among the earliest bridges built in Ohio and Indiana.

      Though the National Road was the nation’s most important traffic artery, even in 1912 when this vintage car passed through a typical double-lane bridge near Effingham, Illinois, the surface was dirt and subject to deep ruts and other obstacles. (Photography Collection, Miriam and Ira D. Wallach Division of Arts, Prints, and Photographs, The New York Public Library, Astor, Lenox and Tilden Foundation)

      Although most sources say Virginia’s Humpback Bridge was constructed in 1835 by Messrs Venable and Kincaid for the Kanawha Turnpike, later research shows that it was constructed in 1857 by an unknown builder. This narrow soil-surfaced road ran 208 miles from the James River to the Kanawha River through central Virginia. (Terry E. Miller, 2012)

      Chillicothe, Ohio’s Bridge Street Bridge over the Scioto River, was built in 1817 to carry the Zanesville to Maysville Turnpike and lasted until its demolition in 1886. Originally built as two covered “tied arch” spans with a long trestle approach on the north end, the latter was replaced in 1844 with a covered multiple kingpost truss bridge. Workers, unable to disassemble the bridge, finally burned it. (Ross County Historical Society, Ohio)

      The heaviest concentrations of covered bridges, according to Caswell and Kane’s research, were in Pennsylvania, Ohio, and Indiana, though West Virginia and Kentucky appear to have had a great many as well. To illustrate, they have documented 2,068 bridges in Pennsylvania, 4,761 in Ohio, and 598 in Indiana (so far), the earliest in Ohio being 1819 and in Indiana 1831. Beyond Indiana the numbers fall dramatically, and the earliest bridges appear later: 168 for Illinois from the later 1830s, 54 in Missouri from the 1850s, 96 in Iowa from the 1860s. To the north, the numbers fall dramatically: Michigan only 46 from the 1840s, Wisconsin 35 from the 1850s, and Minnesota only 13 from the 1860s.

      Going south the numbers tend to decline. Florida is not known to have had any covered bridges. West Virginia had 255 from the 1830s, Kentucky 838 from the 1830s, and Virginia 104 from the same period. Although North Carolina documents only 135 bridges, one is dated to 1818 and South Carolina only 44 but to the 1820s. Interestingly, Georgia and Alabama document 180 and 117 bridge respectively, both from the 1830s, while Tennessee and Mississippi had far fewer, 34 and 12 respectively, from the 1840s.

      Once you cross the Mississippi River, there were few covered bridges until you reach the west coast: California had 98 from the 1850s onwards and Oregon 720 from the 1860s. Between Mississippi and California, the few documented bridges were mostly for railroads: 4 in Arkansas after 1840, 8 in Texas after 1850, 13 in Kansas after 1859, 7 in Nebraska after 1879, and a few scattered bridges, mostly on rail lines, in Wyoming, Arizona, and Washington, all from around the turn of the century. Ten states are not known to have had any, including Florida, Louisiana, Oklahoma, the Dakotas, New Mexico, Colorado, Utah, Montana, and Idaho. Surprisingly, however, Alaska had 7 from the 1920s and Hawaii is known to have had at least 2.

      Closely related are thousands of open wooden trussed rail bridges built and rebuilt over the decades, virtually all using the Howe truss with its adjustable iron rod verticals. They were built open so as not to capture the smoke and hot ashes from the steam locomotives, but because they were open, they rarely lasted longer than ten years. Although few in number, there were here and there covered aqueducts on the canal systems that developed throughout the Middle Atlantic and Midwestern states in the first half of the nineteenth century. Today, fully covered rail bridges only survive in New England, but in the past they were relatively common in the Midwest and even as far west as Washington State. What percentage of the total number of bridges survives? While it is possible to compute these based on the number of known bridges divided into the number of surviving bridges, the results vary wildly, from 1.5 percent in Kentucky to 23 percent in Washington. For most states where such bridges started early and were built in profusion, the number is in the 2–8 percent range.

      Lewis Wernwag’s elegant bridge over the Kentucky River at Camp Nelson in Jessamine County, Kentucky, carried the Lexington Road when it was built in 1838 at a cost of $30,000. A double-lane span 240 feet long, it continued to carry US 27 until a truck broke through the floor in 1926, but the bridge remained until 1933. The Union Army established Camp Nelson in 1863 as a depot to supply its forces in Kentucky and Tennessee. (Wells, 1931: 77)

      Hawaii’s few covered bridges, all gone now, were not quite comparable to those on the mainland. This open-sided kingpost bridge, apparently going uphill near Hilo, photographed around 1880 may have been a footbridge. (Hawaii State Archives)

      Alaska had perhaps a dozen or so bridges, all of the Western Howe design built after 1900. These “twin bridges” were on the Seward-Anchorage Road in south central Alaska and were removed before 1959. (Alaska State Library)

      Spanning Salt Creek at the north entrance to Indiana’s Brown County State Park, the Ramp Creek Bridge was originally built in 1838 just south of Fincastle in Putnam County on what became US 231. This bridge, built by Henry Wolf and Chilion Johnson, is both Indiana’s oldest and its only “double-barrel” bridge. It was moved here in 1932. (A. Chester Ong, 2011)

      This historical photo taken in the early 1870s shows Obadiah Wilcox’s 1813 highway bridge over the Sacandaga River near Hadley in Saratoga County, New York. Behind it is a four-span open deck Howe truss bridge carrying the Adirondack Railroad’s first engine, the General MacPherson. The rail bridge was built in 1870 but by 1905 all spans had been replaced. (NSPCB Archives, R. S. Allen Collection)

      Using a combination open Post truss, this rail bridge over Clear Creek in Colorado’s Clear Creek Canyon was probably built to serve the state’s gold rush, which began in 1859. The line eventually became the Colorado Central