I'm putting this here because I think by 1900 it would have been much harder.
The general idea I have is for a state already in the Union to be split into two or more successor states inside the United States. I think the best candidates for this are Texas (which I think already has a provision from when the Republic of Texas was admitted), California (North and South split) and New York (NYC and Upstate Split).
The general idea I have is for a state already in the Union to be split into two or more successor states inside the United States. I think the best candidates for this are Texas (which I think already has a provision from when the Republic of Texas was admitted), California (North and South split) and New York (NYC and Upstate Split).