1812: Territory of Louisiana reorganized into the Missouri Territory containing much of eastern and north western Wyoming.

1850: Territory of Utah organized containing southwest and south central parts of Wyoming.

1853: West central Wyoming becomes part of the Oregon Territory.

1854: Missouri Territory reorganized and Nebraska Territory receives much of eastern and north western Wyoming.

1859: Oregon admitted as a state and west central Wyoming is added to the Washington Territory.

1861: Utah Territory reorganized and south west/south central Wyoming is added to the Nebraska Territory.

1863: Washington Territory reorganized and west central Wyoming is added to the Idaho Territory. The Dakota and Nebraska Territories are reorganized and the north half of Wyoming is added to the Idaho Territory.

1867: Nebraska admitted as a state and the south half of Wyoming is added to the Idaho Territory.

1890: Wyoming admitted as a state.