The early USGS bench marks in Nebraska were established on at least four different datums. The "OMAHA" datum was based upon two bench marks in Iowa (P.B.M. 327 and P.B.M. 336) that were established by the Missouri River Commission in 1892. The "YNKTN" datum was likewise referenced to a Missouri River Commission bench mark (355/1) located near the town of Ponca, Nebraska. The abbreviation is for the word "Yankton" where many of the bench marks are located near Yankton, South Dakota. The "ADJ 1903" datum was from one of the same bench marks used early for the Omaha datum (P.B.M. 327), but with an adjusted elevation. The "SIDNEY" datum has its origin from an elevation supplied by the Union Pacific Railroad on one of their bridges over Lodgepole Creek approximately four miles east of Sidney.
UNITED STATES
GEOLOGICAL SURVEY
(Early Bench Marks in Nebraska)
1143
1466
DATUM
1027
DATUM
NAIL
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© Jerry Penry 2010