Sketch K Showing the Progress of the Survey of the Columbia River Oregon

Triangulation chart of the entrance to the Columbia River extending from Cape Disappointment (or Hancock) and Cape Adams eastward to Three Tree Point. The maps shows many locations and triangulation station points, rivers, Astoria, Gray's Bay, and Lewis & Clark River.

IMPORTANT NOTE:

All of our United States Coast Survey (USCS), United States Coast & Geodetic Survey (USC&GS), and similar maps and charts have been professionally unfolded and flattened using humidity baths, semi-permeable membrane, and drying blotter techniques. Most others you typically see on eBay have not been, and worse, are quickly and crudely unfolded for the low-quality photos you see. Unfolding these maps in that way is damaging and weakens them. Please be aware.