Learn About
The Commemorative
Quarter for
The Commemorative Quarter for Montana

Time Zone: Jefferson County lies in the Mountain Time Zone (MST/MDT) and observes daylight saving time.

The community of Boulder is the Seat for Jefferson County.

Jefferson County is one of the original counties of Montana and was founded in 1864.

From the Census Estimates for 2009, <1> Jefferson had a population of 11,470 people. This is an increase of 14.14% since the last Census (which gave a population of 10,049 people in 2000).

At the time of the 2000 Census, Jefferson represented 1.11% of the total population of Montana, making it the state's 19th most populous county (out of 56 counties).

The following table shows the recent changes in population. Other than 2000, the population counts have been estimated by the Census Bureau.

Since 2000
Year-to-Year Change
201011,406+13.5%-0.56% since 2009
200911,470+14.14%+1.61% since 2008
200811,288+12.33%+1.45% since 2007
200010,049The Last Census

More information can be found on the Jefferson County Census Page for Jefferson County.


Websites for Jefferson County

Official Website:   www.co.jefferson.mt.us/

If you know of a history or genealogy society whose interest includes Jefferson County, would you please send us the URL for their website? We would like to add their link to our Gazetteer. To contact us, please visit our Feedback Page.

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Footnotes ...

<1>On a yearly basis, the US Census Bureau creates an estimate of the county's population. Keep in mind that this is an estimate and not an actual count. The last physical count was the 2000 Census and the next count will be for the 2010 Census.

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<2>All Quarter-dollar coin images from the United States Mint.

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