Originally Posted By: hikermor
Only 30 years? Working at Channel Islands National Park, I used topo maps that were produced in 1943. .The basic topography from that era is still in use today, more than 70 years later. Using them routinely from 1982, I found that the topography was usually spot on. Not so with cultural features, but that is why you carry a pen and pencil.



Yes, I have used some very old ones as well. As long as you know the current declination for converting you magnetic azimuth to grid, and visa versa, then you are good to go. It gets really interesting when you are using some ancient mining maps produced in another language in a country where quality control does not exist. Makes for some interesting walks.