This layer includes the 15', 1:62500 USGS topographic maps for Maine from the mid 1900s, mostly ranging from 1920 to 1965. There are 190 quads in this layer, covering all of the state. Eight quads did not have maps from this era, so their earlier maps were used and are duplicates from the circa 1910 series for Maine as early as 1904. These are Petit Manan (1904) Monhegan (1906), Tenants Harbor (1906), Matinicus (1906), Belfast (1917), Cutler (1918), and Great Wass Island (1921). The maps were scanned from paper copies, georeferenced, and then had the collars clippled and the edges mosaicked. Most maps were scanned originally at 600dpi, either by MEGIS or USGS. All georeferencing of these was done by USGS. A few quads were not either in the collection of Maine or USGS, and in those cases quarter-quads were downloaded from the UNH library web site, those quarters were then georeferenced separately and if needed, rubber-sheeted along seamlines to make the quad. Most of these quads indicate land cover (green areas). Note that the source paper maps vary considerably in their paper color, ink contrast, fading, and so forth. The user will see great variation between quads which cannot be made more consistent at this time.

This layer includes the 15', 1:62500 USGS topographic maps for Maine from the mid 1900s, mostly ranging from 1920 to 1965. There are 190 quads in this layer, covering all of the state. Eight quads did not have maps from this era, so their earlier maps were used and are duplicates from the circa 1910 series for Maine as early as 1904. These are Petit Manan (1904) Monhegan (1906), Tenants Harbor (1906), Matinicus (1906), Belfast (1917), Cutler (1918), and Great Wass Island (1921). The maps were scanned from paper copies, georeferenced, and then had the collars clippled and the edges mosaicked. Most maps were scanned originally at 600dpi, either by MEGIS or USGS. All georeferencing of these was done by USGS. A few quads were not either in the collection of Maine or USGS, and in those cases quarter-quads were downloaded from the UNH library web site, those quarters were then georeferenced separately and if needed, rubber-sheeted along seamlines to make the quad. Most of these quads indicate land cover (green areas). Note that the source paper maps vary considerably in their paper color, ink contrast, fading, and so forth. The user will see great variation between quads which cannot be made more consistent at this time.