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.

South Carolina general information:  About nine historic covered bridges survived in South Carolina in 1950; today, only one remains, Campbell Bridge in Greenville County, a Howe Truss Bridge, built in 1909.  Campbell Bridge has been the solitary survivor since 1982, when Lower Grassaway Bridge collapsed into Twelvemile Creek.  Of the twenty five covered bridges in South Carolina, only one is authentic.  Fifteen are foot bridges, and seventeen are located within a twenty five mile radius of Greenville, in Greenville County and three adjoining counties; Laurens, Pickens and Spartanburg.  The twenty four non authentic modern bridges were constructed in the 21 year span from 1980 to 2000.