The counties gaining the most residents from moves

The ranking below covers the 285 counties with at least 40 listed origin and 40 listed destination counties in the IRS files. Together they file about 65% of all returns in the counties with complete data, so most large and mid-sized counties are in it. The measure is the net migration rate: returns that moved in minus returns that moved out, per 1,000 returns filed in the county.

Pinal County, Arizona, leads with a net gain of 40.1 per 1,000. Pinal sits between Phoenix and Tucson, and its largest source of arrivals is neighboring Maricopa County. Florida dominates the rest of the list, with 10 of the top 20, spread from the Panhandle to the Atlantic coast. South Carolina has 2 and Texas 3.

Pinal’s lead is not only a matter of rate: its net gain of 6,742 returns also places it among the ten largest absolute gains in the country, a rare combination for a county of its size: it files 168,266 returns, against 1,813,480 in neighboring Maricopa.

Rate versus size

A rate rewards counties that are growing quickly for their size. A different list appears when the net gain is counted in returns. Here the large suburban counties of Texas and Florida come forward, because a moderate rate applied to a big base produces a large number.

Polk County, FL, and Pasco County, FL, head that list, each adding more than 9,000 returns on balance. Several of the leaders sit on the edge of a large metro area: Montgomery County outside Houston, Williamson County outside Austin, Collin and Denton Counties outside Dallas.

The fastest losses

At the bottom, the picture is one of big cities and a few college towns. Bronx County, New York, had the lowest rate of these 285 counties at −28.8 per 1,000, and 2 New York City boroughs appear among the 15 lowest. Two counties built around a large university are also on the list: Tippecanoe County in Indiana, home of Purdue, and Washtenaw County in Michigan, home of the University of Michigan.

In absolute terms, Los Angeles County, CA, lost 40,453 more returns than it gained, nearly twice the loss of Miami-Dade County, FL, the next on the list. Los Angeles is so large that this comes to −9.9 per 1,000, a rate that is low but not extreme.

How common is a gain?

Of the 2,748 counties with complete totals, 1,452 gained returns through moves in 2022–23, a little more than half. Among the 285 counties with at least 40 listed partners in each direction the split is the other way: 130 gained and 155 lost. Large urban counties weigh on that split: 23 of the 30 largest of them lost returns on net.

State by state

Florida has more of these 285 counties than any other state, 29, and 21 of them gained returns through moves. Texas follows the same direction with 14 gainers out of 20. California is the mirror image: only 3 of its 24 gained, and in New York and New Jersey the count is 2 of 13 and 2 of 13. Pennsylvania has 3 gainers out of 14.

These counts describe the larger counties only. A state can lose returns in its big urban counties and still gain overall, as the state pages show for moves between states.

Turnover behind the balance

The net rate hides how much moving goes on. Arrivals plus departures, as a share of a county’s returns, give a turnover figure. Among these 285 counties, the median turns over 13.8% of its returns in a year. The City of Alexandria and Arlington County in Virginia have the highest turnover, above 30%, yet both ended 2022–23 close to balance. Hidalgo County, Texas, has the lowest at 5.6%.

Reading the ranks with care

A net figure is the difference between two much larger flows. A county can rank near the middle while hundreds of thousands of returns move through it, and a small change in either direction can move it several places in the ranking from one year to the next. The county pages show both flows, and the four-year chart on each page shows whether a rank reflects a steady pattern or a single year.

The data also says nothing about why people moved. Reasons such as housing, work or family are not recorded; the IRS files hold only the change of address. For the counties in these tables, the full lists of where arrivals came from are one click away, and the county tracer covers every other county with complete totals.

Sources

IRS Statistics of Income, SOI Tax Stats – Migration Data, county-to-county and state-to-state files, 2019–20 to 2022–23 (irs.gov). County locations: US Census Bureau, 2023 Gazetteer Files. Calculations by countymoves; definitions in How to read the data.