So after watching "How the States got their shapes" the other night I went about looking for more information as obviously a television program is going to have to cut out a lot of the information and basically give a summary.
I found this very informative document on how Idaho got its name (apparently it was made up) and its shape (see from page 5 onwards). It also details how Washington and Montana got their shapes as well and has some super-useful maps at the end. So for anyone wishing to come up with alternate state borders and names I think this will come in handy.
Having read it, it seems that had Congress paid attention to the proposal of the Idaho territorial legislature (a proposal which was agreed to by the Montanan miners' legislative representatives) then Idaho and Montana would have been divided along the Continental Divide and not the Bitterroot Range and eventually (by 1866) the Idaho legislature would have been calling for the creation of a new territory out of the north of Idaho (due to the difficulty in communication between northern Idaho (centered on Lewiston) and southern Idaho (centered on Boise)). They had proposed a territory of Columbia in 1866 in OTL from what is now northern Idaho, Montana west of the Continental Divide and parts of Washington territory but if this alternate proposal (which would exclude any parts of Washington territory) were put into effect then perhaps this new territory of *Shoshone or * Missoula or *North Idaho would have had a population of about 669,000 (more than Vermont's) in 2010 (assuming that everything else went pretty much as in OTL) and would probably be a State today. Of course Montana and (rump-) Idaho would be smaller in size and population. Montana would have about 657,900 (still more than Vermont) and Idaho would have had 1,239,500.
Here's a map of what it would have looked like in May 1864:
I found this very informative document on how Idaho got its name (apparently it was made up) and its shape (see from page 5 onwards). It also details how Washington and Montana got their shapes as well and has some super-useful maps at the end. So for anyone wishing to come up with alternate state borders and names I think this will come in handy.
Having read it, it seems that had Congress paid attention to the proposal of the Idaho territorial legislature (a proposal which was agreed to by the Montanan miners' legislative representatives) then Idaho and Montana would have been divided along the Continental Divide and not the Bitterroot Range and eventually (by 1866) the Idaho legislature would have been calling for the creation of a new territory out of the north of Idaho (due to the difficulty in communication between northern Idaho (centered on Lewiston) and southern Idaho (centered on Boise)). They had proposed a territory of Columbia in 1866 in OTL from what is now northern Idaho, Montana west of the Continental Divide and parts of Washington territory but if this alternate proposal (which would exclude any parts of Washington territory) were put into effect then perhaps this new territory of *Shoshone or * Missoula or *North Idaho would have had a population of about 669,000 (more than Vermont's) in 2010 (assuming that everything else went pretty much as in OTL) and would probably be a State today. Of course Montana and (rump-) Idaho would be smaller in size and population. Montana would have about 657,900 (still more than Vermont) and Idaho would have had 1,239,500.
Here's a map of what it would have looked like in May 1864:
