"Compiled from 1:24,000- and 1:62,500-scale topographic maps dated 1928-1964." "Planimetry revised from aerial photographs taken 1974 and other source data." Available also through the Library of Congress Web site as a raster image.
United States. Soil Conservation Service
<a rel="nofollow" class="external free" href="https://www.loc.gov/item/81690020/">https://www.loc.gov/item/81690020/</a>