Posted in Research tips, State records, Territorial records

When was it a territory? When was it a state?

Mountain West FB

Here is a reference table to help you see at a glance when each state in the Mountain West was first a territory and then a state. I have also added a column for history which gives some key dates in each state’s history.  Feel free to copy this table for your own use.

After you have pinpointed where your ancestor was living, working, or passing through at a given time, it is important to find out what country/state/ territory/county had jurisdiction in that locality on that date. That will tell you where the records can be found—or at least who was creating the records. You may be surprised to find that Arizona ancestor in New Mexico territorial records, or that Nevada ancestor in Utah territorial records. And Colorado ancestors?  Take your pick of Nebraska, Kansas, Utah, or New Mexico territories…

Stay tuned for some advice on where to look for the records, especially territorial records—an important record group for research in any western state.  Click on the map link in the menu bar to access map resources which will be helpful in determining boundaries and jurisdictions.


I am an Accredited Genealogist® professional living in California. I have been researching and teaching since 1988.

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