Humboldt County was designated as a county in 1856 by the Utah Territorial Legislature and again in 1861 by the new Nevada Legislature.
Lyon County is Nevada’s third most populous county. It was one of the nine original counties created in 1861 and was named after Nathaniel Lyon, the first Union General to be killed in the Civil War.
Lake County, one of the original nine counties formed in 1861, was renamed Roop County in 1862. Part of the county became Lassen County, California in 1864. The portion that remained in Nevada was annexed in 1883 by Washoe County.
In 1970 Ormsby County was dissolved and the Consolidated Municipality of Carson City was created by the Legislature in its place.
Bullfrog County, was formed in 1987 from part of Nye County. After creation, it was declared unconstitutional. The county was abolished in 1989.
As of 1919 there were 17 counties in Nevada, ranging from 146 to 18,159 square miles.