On the eve of the Civil War, Kansas was admitted into the Union; during the war, the Territories of Colorado, Nevada, Dakota, Arizona, Idaho, and Montana were organized, and Nevada was admitted as a State.

Immediately after the war, Nebraska was admitted and Wyoming was organized as a Territory.
In the Centennial Year (1876) Colorado became a State.

In 1889 and 1890 North and South Dakota, Montana, Washington, Idaho, and Wyoming were admitted as States.

In the latter year Oklahoma was carved out of the Indian Territory.

Utah with its Mormon population was kept waiting at the doors of the Union until 1896.