The 100th longitudinal line west of Greenwich was the major goal set by Congress in building the first transcontinental railroad.
Construction of the Union Pacific track reached the Meridian on October 5, 1866.
To celebrate this record-breaking achievement against terrific odds, appropriate ceremonies were enacted on this ground on October 26, 1866.
A "Great Excursion from Wall Street to the 100th Meridian brought 250 notables including railroad and territorial officials, congressmen, financiers and newspaper men on the first passenger train to run west of the Missouri River.
A large signboard proclaiming the "100 Meridian 247 Miles from Omaha" stood for many years close to the track on the Meridian but finally disappeared, and in 1933 was replaced on the original site with a monument of native stone by the Cozad Chapter of the D.A.R.

In 1879 John Wesley Powell, U. S. Army, in his report for the Geological Survey recognized the 100th Meridian as the natural demarcation line extending northward from the western shore of the Gulf of Mexico.
Evaporation from the gulf waters supplies most of the rainfall east of the Meridian.
West of the Meridian precipitation comes largely from the Pacific which is generally insufficient for agricultural needs without irrigation.
Here on the 100th Meridian, Humid