A comprehensive set of Ordnance Survey sheets for the Metropolitan Wigan area is available. The original Ordnance Survey maps were not located on a nationwide National Grid, but as a series of maps each based on an individual county. They are often referred to as the county series or six-inch maps of c1847.
The 25-inch series was based on the six-inch maps. Each grid was divided into 16 and numbered in the same way.
- The first edition was published between 1892 - 1894
- The second edition 1908 - 1910
- The third edition 1927 - 1929
- There is also an incomplete, advanced edition of 1936 - 1937.
The 2.5-inch to a mile scale or 1:25000 was brought out c.1952. The National Grid survey references contain letters and numbers. The archive holds later copies of these maps from the 1950s to 1990s.