World Guide Covered Bridge (WGCB) numbers have been assigned by the National Society for the Preservation of Covered Bridges (NSPCB) are referenced for all listed bridges.  Assigned numbers are coded, such as NH-05-12 or VT-115-a.  The first two characters are the postal abbreviations for the state (formerly digits starting at 01 represented the state in alphabetical order).  The second two digits represents the county in alphabetical order starting at 01 for each state.  The third pair of characters represents the bridges place in the NSPCB tally of that county's bridges, starting at 01 for authentic truss type bridges or a letter for non-authentic type bridges, an upper case letter for motor vehicle bridges, and a lower case letter for footbridges. Additionally, bridges that have a leading "(" before the last letter, are considered O.C.B.I. - "Of Covered Bridge Interest" - a Covered Bridge that is under 12' or is just on the ground and not over anything, i.e., 45-12-(b.

Vermont - General information. One of Vermont's nicknames is "The Covered Bridge State." This nickname is justifiably applied because Vermont holds the distinct honor of having more covered bridges within its borders, per square mile, than any other state in the Union. There are records of well over five hundred covered spans that once stood in Vermont. While that number has decreased, nearly one hundred historic structures can still be found. The earliest authenticated date for a covered bridge in Vermont is 1824. It was a long, single span, arched truss bridge, across the Mississquoi River at Highgate Falls, Vermont. The Town lattice truss appears to be the truss of choice throughout much of the state although several of the other truss styles are also well represented. However in the northern part of the state, the Burr Arch truss was the preferred. Spread throughout the state are numerous examples of the multiple Kingpost and the Queenpost truss. There is also one Haupt truss, one Pratt truss, and three Paddleford Truss covered bridges.