Most of the area that is now Wyoming, except for a small attachment remaining with Idaho territory, became part of Dakota territory in May of1864, for a four-year period until Wyoming, itself, became a territory in 1868. Not the lightly engraved…
For the fourteen-month period from March 2, 1863, to May 26, 1864, the area that is now Wyoming was part of Idaho territory. On the same 1864 date, Montana became a territory. Sparse population made these jurisdictional changes of little importance.