Originals & processed scans

Historical maps

Compare original scans with processed displays. Zoom to inspect contours, lettering and symbols.

1920 bulletin · bound 1922 · Restored display

Parker’s Westchester County map

A complete retained sheet of Arthur C. Parker’s numbered inventory, with its red site marks, place names, coastline and legend.

2000 × 3249 retained source → 4000 × 6498 display

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Arthur C. Parker · New York State Museum · Internet Archive scan

Native 1892 Croton-area map excerpt; original and processed files linked below

April 1892 edition · surveyed 1890 · Restored display

Croton area, 1892

Twenty-foot contours, roads, streams and place names before the New Croton Reservoir.

6750 × 4600 retained source → 6750 × 4600 display

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U.S. Geological Survey · Frank Sutton and Robert Muldrow, topography · USGS HTMC

Native 1937 Croton-area map excerpt; original and processed files linked below

1937 Army reprint · 1915 fieldwork · Restored display

Croton area, 1937

Ten-foot contours, roads, buildings and water detail on the Army tactical-map reprint.

7750 × 5550 retained source → 7750 × 5550 display

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Corps of Engineers, U.S. Army · USGS engravings · Library of Congress / USGS HTMC

How a map reaches this collection

Keep the source file, its provenance and checksum.
Process at verified native resolution first. Document paper and ink corrections and disclose any display enlargement.
Inspect source comparisons, small lettering, contour gaps, symbols and tile edges. Record the scope of each review.
Release a reversible display derivative with the original alongside it.

Upscaling interpolates the scan. It cannot recover an unreadable word or establish a more accurate historical location. Vector tracing is tested separately; candidates that alter marks stay out of the public map.

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