This document contains an abbreviated history of the establishment of the North American (US and later Canada and Mexico,) horizontal control(benchmark) network

This document contains an abbreviated history of the establishment of the North American (US and later Canada and Mexico,) horizontal control(benchmark) network that allowed for the precise description of the location of land pre-GPS. The history part starts on page 19. https://www.ngs.noaa.gov/PUBS_LIB/TRNOS88NGS19.pdf https://www.ngs.noaa.gov/PUBS_LIB/TRNOS88NGS19.pdf