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You searched for: Time Period 1950-1999 Remove constraint Time Period: 1950-1999
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1.
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104 State Water Plan Watersheds: Pennsylvania

1998. Environmental Resources Research Institute. Digitized boundaries of 104 major watersheds defined in the Pennsylvania state water plan. The State Water Plan, originally developed in the 1970s,...

10.
Abandoned railroads of Indiana.

Abandoned railroads of Indiana.

1960?. Pen and ink.; Base map: Geological Survey (U.S.). State of Indiana, Scale 1:500,000, Washington, D.C., 1950. Scale approximately 1:2,027,520.

11.
Academy Gletscher: Greenland

Academy Gletscher: Greenland

1953. Projection: Polar Stereographic Projection; Series: AMS C501 Greenland 1:250,000 Topographic Series.

12.
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Active Railroads: Pennsylvania

1996. Environmental Resources Research Institute. Location of active rail lines in Pennsylvania, digitized from 1:24,000 USGS topographic maps on a stable Mylar base.