The Expansion of the National Spatial Reference System: 1816 - 2006
You may need to download: Quicktime
This movie depicts the expansion of NOAA's national survey network, which is called the National Spatial Reference System (NSRS). The survey work depicted in the animation, which defines the latitudes and longitudes of marked points, began in 1816-1817 in New York Harbor, when the newly created Survey of the Coast undertook its first field project. The movie begins in the year 1817, with one white dot over New York Harbor representing this first survey project. Each frame of the movie is one year and each dot represents the establishment of subsequent survey marks.
For several years after 1817, there was no progress in the expansion of the network, due to administrative changes and delays. The work continued in 1832, with surveys expanding northeasterly into New England. The work then expanded southerly along the East Coast, to the Gulf Coast, and to parts of the West Coast in 1851.
In 1871, a major effort, known as the Transcontinental Arc of Triangulation, was undertaken to conduct a very precise survey across the country. This is clearly seen in the animation by 1890, as a series of blue dots across the middle of the U.S.
By 1930, the survey network stretched across the country and began to form a “lattice” pattern as more parts of the country were surveyed. This lattice brought precise survey control to most parts of the country.
During the early 1930's, Great Depression relief programs expanded the size of field survey crews. These crews made tremendous progress in expanding the survey network—progress shown in the movie as the country was filled in with green dots by 1935. Later, the density of survey control points in Alaska and other areas was increased.
Today, there are over 1,500,000 positioned points in the National Geodetic Survey's database and which are part of the NSRS.