World Guide to Covered Bridges
The World Guide to Covered Bridges is a covered bridge numbering system invented by John Diehl, the chairman of the Ohio Covered Bridge Committee. The committee first used the numbering system in 1953 to publish a list of covered bridges in Ohio.
The most recent World Guide was published by the National Society for the Preservation of Covered Bridges in 2009. Updates to the 2009 edition are available as a PDF file.
