North America

Page Base Line

In the late nineteenth century the U. S. Coast & Geodetic Survey undertook measurements to determine the nation’s physical shape with absolute accuracy. This survey initially involved two triangulation networks. One survey stretched from coast to coast, while another stretched from Mexico to Canada. The north-south survey, known as the 98th Meridian Survey, came through central Nebraska during 1898-1901. Angles from observation towers were turned at night to lights on other towers located many miles apart. The distances between the points were computed mathematically by trigonometry.