Article Index

A. Introduction

In the XII. Datums topic we saw that the national network grew from ~27,000 horizontal control points in NAD 27 to over 270,000 for NAD 83. In the 35+ years since, the National Spacial Reference System (NSRS) has grown to over 680,000 horizontal, vertical, and combined control points. The NGS maintains an internet accessible digital database of control information. Users are able to locate control points by name, location, proximity, rectangular area, or topoquad.

This chapter is a very basic description of the general data content for control point retrieval. Due to point type diversity, measurement technologies, multiple readjustments, etc,. specific data will vary point to point.

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