At a time when population growth in the United States has fallen to a historically low rate, the Intermountain West has become one of the fastest growing regions in the country.

In 2021, the four fastest growing states were all in the West, according to U.S. Census data.

Idaho was the fastest-growing state with 2.9% growth from 2020 to 2021. Utah and Montana tied for second at 1.7%, followed by Arizona, at 1.4%.

Nevada was the only other Intermountain West state in the top 10. With 1% growth, it tied Florida for eighth.

Top 10 states in percent growth, 2020 to 2021


State, percent growth


  1. Idaho, 2.9%

2. Utah, Montana, 1.7%


4. Arizona, 1.4%


5. South Carolina, Delaware, 1.2%


7. Texas, 1.1%


8. Florida, Nevada, 1%


10. South Dakota, 0.9%


Source: U.S. Census Bureau

Overall, U.S. population growth in 2021 reached its slowest rate since the nation’s founding, the Census found. America’s low 0.1% growth rate was due to lower birthrates and migration, as well as COVID-19, which killed more Americans this year than in 2020.

The previous record for slowest population growth was set from 1918 to 1919, during the Spanish flu pandemic and World War I.

“Population growth has been slowing for years because of lower birthrates and decreasing net international migration, all while mortality rates are rising due to the aging of the nation’s population,” Census Bureau population division demographer Kristie Wilder said in a statement. “Now, with the impact of the COVID-19 pandemic, this combination has resulted in a historically slow pace of growth.”

Top 10 states in numeric growth, 2020 to 2021


State, numeric growth


  1. Texas, +310,288

2. Florida, +211,196


3. Arizona, +98,330


4. North Carolina, +93,985


5. Georgia, +73,766


6. South Carolina, +59,976


7. Utah, +56,291


8. Tennessee, +55,099


9. Idaho, +53,151


10. Nevada, +29,920


Source: U.S. Census Bureau


Out West, however, growth was driven by a natural increase of 143,082 people, and a positive net international migration of 38,347 people. The growth in states like Idaho, Utah, Montana and Arizona offset a decrease in California. California saw its population fall by -0.7%, the first decline in state history.

There are political implications for the recent population shifts. While California remains the most populated state in the country with more than 39.2 million residents, it’s losing one congressional seat for the first time in its history. Meanwhile, Colorado, Montana and Oregon are each picking one seat up.

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In Arizona, growth in highly educated, upper-class suburban areas in Maricopa County has helped Democrats win in a competitive conservative state, while anxieties over a flood of liberals moving in has influenced the political culture of Idaho, where many see their state as a last safe space for conservatives. Boise State University’s 2021 Idaho Public Policy survey found 78.3% of Idahoans believe Treasure Valley, which includes Boise, is growing too fast.