BOISE, Idaho — Nampa and Caldwell are among the Treasure Valley cities that have more than doubled in population in the last 20 years, according to new data the Community Planning Association of Southwest Idaho (COMPASS) released last week. 

Also, the Treasure Valley's total population in Canyon County and Ada County has now passed 712,000 residents. In the 2010 Census, the counties combined for 581,288.

The population increase in Meridian and parts of Canyon County is significantly surpassing that of Boise as Treasure Valley growth continues to expand west. 

The COMPASS estimates are based on calculations of how many people live in each home within a city's limits and other factors including building permits, Idaho Power data and more.

Nampa, with a population of 102,030, has become the third Idaho city to reach 100,000 people, according to COMPASS estimates. Nampa has doubled in size in nearly 20 years, from 51,000 in the 2000 Census. In the last four years, the city has added 13,000 people.

The other Canyon County city that more than doubled in the last 20 years was Caldwell, which expanded from 25,968 in 2000 to an estimated population of 58,830 in 2019. The city gained nearly 7,000 new people since 2015. 

Canyon County now has an estimated total population of 224,530, which includes unincorporated parts of the county. 

RELATED: Meridian's population surpasses 100,000

In Ada County, Meridian, with a population of 114,680 in 2019, saw the addition of over 8,000 people in just one year, between 2018 and 2019. That's the largest year-to-year growth in the entire Treasure Valley. In the last four years, Meridian's population increased by 23,370. In 2000, Meridian's population was 34,919. 

Boise, now at 236,310 residents, grew by 4,000 between 2018 and 2019. 

Ada County inches closer to the 500,000 mark with a total population of 487,670, growing by roughly 17,000 from the 2018 estimates.

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