County of bridge: Monroe County
Location of bridge: MO C, Union Covered Bridge Historic Site, W. of Paris
Marker erected by: Missouri Department of Natural Resources, Division of State Parks
Union Covered Bridge:
This bridge, completed in 1871 by bridge builder Joseph Elliot, is the only Burr Arch truss still standing in Missouri. Located eight miles southwest of Paris in Monroe County, the bridge measures 120 feet long and is 17 feet, 6 inches wide
Union Covered Bridge was built almost entirely of native oak. Oak is a common wood in northeast Missouri, easily available, hard, durable, and reasonably easy to work with. All of the wood used in Union Covered Bridge with the exception of the cedar shingles, is oak.
Another interesting feature of Union Covered Bridge is that the siding is horizontal, as it would be on a house; the other covered bridges in Missouri have vertical siding, as would be found on a barn.
In the 1800s and early 1900s, posters wee an important means of advertising that lined the roadways much like billboards do today. The covered bridge, because of the protection it offered, became a prime spot for these richly colored advertisements.
Posters advertising everything from the latest miracle cure to the newest sewing machine, from the big circus coming to town to the best turnip seeds.
The many nooks and crannies is an uncovered bridge trapped dirt and moisture. This was ideal for decay of the timbers. Uncovered bridges exposed to the elements had a normal life expectancy of around ten years. Covered bridges roofed over to increase their longevity by protecting the trusses from the elements. As one contemporary expressed it, bridges were covered for the same reasons women wore petticoats - "... to protect their underpinnings." Other advantages also resulted:
1. The barnlike structures helped reassure farm animals about to cross.
2. The roofed structures served as emergency shelters.
3. The covering added to the strength of the bridge, reducing the sag and creaking commonly found in
uncovered wooden bridges.
Treenails (see gallery), pronounced "trunnels", were wooden pegs used in place of nails to hold the bridge together. Made on a lathe, they were anywhere from 1 to 2 inches in diameter and 10 to 12 inches long. As many as 900 treenails were used on a covered bridge 100 feet long
Scarf and stepped joints and lap joints (see gallery) were used to obtain chords of more than 100 feet. Both used on upper and lower chords are necessary in the construction of a bridge. A third joint, the mortise and tenon were used where web members connected to the kingpost.
Each truss member was individually fashioned simplified final assembly of the truss structure by stamping Roman numerals in the ends of the timber to be joined.