In 1866, Colorado's first bid for statehood passed Congress, but was vetoed by President Andrew Johnson who cited concerns with Colorado’s population:
The population [of Colorado] is small; some estimate it as low as twenty-five thousand, while the advocates of the bill reckon the number at from thirty-five thousand to forty thousand. The people are principally recent settlers, many of whom are understood to be ready for removal to other mining districts beyond the limit of the Territory, if circumstances shall render them more inviting
