Merrick County was formed in 1858 and organized in 1864. It was named for
Elvira Merrick, the maiden name of the wife of territorial legislator Henry W.
DePuy, who introduced the bill that created the county.
When first formed, the county was bounded on the south by the Platte River,
and by straight lines on the north, east, and west. It thus included 180 square
miles (470 km2) of the Pawnee Reservation, established one year
before the county. In 1873, the state legislature removed these reservation
lands from the county, leaving it with a jagged northern border from which
narrow panhandles extended northward from the northeast and northwest corners.
In 1897, the Pawnee Reservation became Nance County.