Just note that there is a problem dating these maps, you can refer to individual company spread sheets to see examples of dating for those years.
All of these so called "hard-cover" maps I have seen can be dated with a year date that is fairly easy to find either on the map cover or on the map itself.There can be different map codes on each sub-map that is part of the overall map.For this discussion I am going to refer to the map code on the large state map on any given state map.But if one looks at the date of the map base code and assumes say 2 revisions per year it usually becomes obvious how to date the map.Dating 19 Rand Mc Nally Maps can be difficult, as many of the 1957 maps have 1956 map codes, this is true for many states and many companies.The 1063 is a base code refering to the map format used for those years by Rand Mc Nally, and the Letter preceeding the base code indicated the year the map was issued.
From 1939 to 1948 General Drafting was the map maker for SOHIO, then in 1949 SOHIO switched back to Rand Mc Nally and started with the new base code of 4903.
SOHIO used Rand Mc Nally maps from 1924-1926, 1930-19-1985.
See the SOHIO-OH-Spreadsheet to see the code sequences Rand Mc Nally used in dating their maps.
The base code identifies a map format created by Rand Mc Nally.
When you look at the SOHIO Ohio maps from 1930 to 1938, you will see that each map code contains the number 1063, and is preceeded by a letter.
This makes it easy to date these maps without opening them up.