Lists of the fastest-growing cities and counties are common, but they only tell part of the story.

Nashville, number one. Clarksville, number two. For the last three years, that has been the story of the state’s fastest-growing communities.

But in Tennessee, the full picture of population change should also include a look at the state’s unincorporated areas which, on the county level, have seen some of the largest population gains so far this decade.

In its hottest start since the 1990s, Tennessee has added over 402,000 new residents since April 1, 2020. And over the last five years, the unincorporated balance of Tennessee counties has grown by 6.3 percent – outpacing the state’s municipalities, which grew by 5.5 percent from April 1, 2020, through July 1, 2025.

Those figures, released by the U.S. Census Bureau last week, underscore the point: some of the state’s most significant growth is happening outside city limits. Since the 2020 decennial census, unincorporated Knox County has added 19,551 new residents – a 7.4 percent gain – making it the third-largest population gainer among all subcounty areas statewide. Each year from 2020 to 2024, unincorporated Knox County ranked between first and fourth among all subcounty areas in annual population gain, adding between 3,800 and 5,400 residents per year. But its growth slowed sharply in 2025 to just 1,079 new residents, while its municipal counterpart, Knoxville, added more than 2,900 new residents. For the decade so far, Knoxville has grown by 6 percent and ranks as the 8th-largest-gaining subcounty area in the state. (Table 1)

The unincorporated parts of Rutherford and Hamilton counties were also among the state’s highest-gaining areas so far this decade. In these cases, the primary municipalities in the county outgained their unincorporated counterparts – Murfreesboro added 18,353 residents to Rutherford County’s 12,693, and Chattanooga added 12,485 to Hamilton County’s 10,430. The fact that both unincorporated areas still ranked in the top 10 statewide underscores just how much population growth lies outside the city limits in these fast-growing counties.

Growth outside city limits presents unique challenges for counties managing the demand for roads, schools, and services – sometimes locating in areas with less developed infrastructure.

Indicators Show Continued Strength for State’s Cities and Towns

In 2025, 209 Tennessee municipalities added population – the fewest since 2021, when 198 communities grew. The dip was in line with the state’s broader return to pre-pandemic growth levels following its largest single-year gain on record in 2024. So far this decade, 254 of the state’s 345 municipalities have added population, surpassing the 207 that grew over the entire 2010–2020 decade.

Municipalities now account for 4.42 million residents – 60.4 percent of the state’s total population, down slightly from 60.5 percent in 2020. That modest dip reflects the faster growth rate in unincorporated areas, even as cities and towns have added 221,100 residents since the last census. (Figure 1).

Figure 1: 2020-2025 Tennessee Municipal Population Overview

Among Tennessee’s fastest-growing municipalities with populations over 20,000, the top six – Lebanon, Gallatin, Spring Hill, Columbia, Smyrna, and Mount Juliet – are all midsized cities surrounding Nashville (Table 2). Three of them crossed the 50,000-resident mark this decade: Lebanon, Gallatin, and Spring Hill. The pattern mirrors what the Census Bureau observed nationally: midsized communities on the edges of major metro areas posted some of the strongest population gains in the country, even as growth slowed in the nation’s largest cities.

Further down the list, Shelbyville’s 11.1 percent population gain stands out. Like Lebanon and Columbia at the top of the table, Shelbyville sits within commuting distance of Nashville and Murfreesboro but offers housing costs which are about 30 percent lower at the median – a dynamic that may be drawing residents priced out of faster-growing markets closer in. Together, the two suggest that Nashville’s growth pressure is radiating well beyond its inner ring of suburbs.

• 20,000 or more
• 5,000 to 20,000
• Less than 5,000

Sizable Revisions Result in a Step Change to July 1, 2024, Populations for Several Municipalities

Census Bureau revisions to prior years’ data don’t normally warrant much attention, but comparisons between the 2024 and 2025 vintage releases for the July 1, 2024, population are worth a second look.

In January, new state-level estimates showed that Tennessee’s July 1, 2024, population had been revised upward by over 23,500 people. That increase was mainly from an adjustment that more accurately reflects where international humanitarian migrants live in the Census Bureau’s Vintage 2025 estimate release. Those changes drew on immigration court records from Department of Justice data, which show the state and county residence of migrants.

This resulted in more than 3,400 new international migrants being added to the 2023 totals. and an additional 20,300 were added in 2024 (Figure 2).

Tennessee was one of 22 states that saw an upward revision to this component and it was among the country’s most substantial—Tennessee ranked fourth-highest nationally, trailing only New York, Texas and Georgia. The largest offsetting decreases to net international migration came from Florida, California, Pennsylvania and Michigan.

At the local level, those revisions have led to significant additions in population, especially for some of the state’s larger communities. In Nashville, the July 1, 2024, population was revised upward by nearly 6,900 people and Memphis saw an additional 3,300 people reported. Several of Tennessee’s other large municipalities also saw bumps as a result of the methodology adjustment. These included Murfreesboro, Chattanooga, Knoxville and several suburban Nashville communities (Table 5)

The City of Oak Ridge saw the 4th largest upward revision among the state’s municipalities. Its revisions were driven by the addition of missing building permit data that primarily affected the Roane County portion of the community. That resulted in a series of changes dating back to 2020 that added 990 people to its 2024 population. Those permits were submitted through the State Data Center’s Housing Unit Review program.

Unincorporated Parts of Tennessee Are Among Fastest Growing Areas Since 2020 © 2026 by Tennessee State Data Center is licensed under Creative Commons Attribution 4.0 International
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