The Migration Mirage: America's Top In-Migration Counties Are College Towns That Barely Grow
Harrisonburg, Virginia has one of the highest in-migration rates in the entire country. Out of every county we score, only three pull in new residents faster as a share of their population. By the logic of every "where Americans are moving" listicle, it should be a boom town in the making.
It is also shrinking. Harrisonburg's population fell slightly over the same year that all those newcomers supposedly poured in. That isn't a contradiction or a data glitch — it's the single most misunderstood number in American relocation data, and once you see it you can't unsee it.
The newcomers are James Madison University students. They arrive in August and many of them leave in May, and the Census counts the arrivals without ever subtracting the departures from the same headline number. The result is a county that looks like a magnet and behaves like a turnstile.
Two numbers that sound identical and aren't
There are two completely different ways to ask "are people moving here," and the gap between them is where the mirage lives.
The first is gross in-migration: how many people moved in over the last year, full stop. This is the number the U.S. Census Bureau's American Community Survey reports, and it's what most "fastest-growing" rankings are quietly built on. It counts arrivals. It does not net out the people who left.
The second is net population change — births minus deaths, arrivals minus departures, the bottom line of whether a place actually got bigger. That's tracked separately by the Census Bureau's Population Estimates Program, and it's the honest answer to "is this town filling up."
For most places, those two numbers roughly agree. For a specific kind of place, they don't agree at all — and that kind of place dominates the top of the in-migration charts.
Why college towns game the chart
The Census counts you where you actually sleep most of the year, not where your parents live. A student who moves into a dorm or an off-campus apartment for more than two months is a resident of that college town, and the survey's "where did you live a year ago?" question turns every incoming freshman and transfer into a fresh in-migrant.
What it doesn't do is flag the graduating senior who moves out the same spring. Both happen every year, in roughly equal numbers, which is exactly why a university county can run a double-digit in-migration rate while its actual population barely twitches. It's a bucket with the inflow pipe wide open and just as much draining out the bottom.
Sort our scored counties by in-migration rate and the top of the list reads like a college-football schedule:
| County | University | In-migration rate | Actual pop. growth |
|---|---|---|---|
| Watauga, NC | Appalachian State | 14.2% | +0.9% |
| Athens, OH | Ohio University | 12.4% | +0.3% |
| Harrisonburg, VA | James Madison | 12.0% | −0.2% |
| Brazos, TX | Texas A&M | 10.2% | +1.8% |
| Isabella, MI | Central Michigan | 9.7% | +0.1% |
| Clarke, GA | Georgia | 9.6% | +0.3% |
| Story, IA | Iowa State | 8.8% | +1.9% |
| Centre, PA | Penn State | 7.7% | +0.3% |
| Monroe, IN | Indiana | 7.7% | +0.8% |
| Montgomery, VA | Virginia Tech | 7.7% | −0.1% |
More than twenty of the thirty highest in-migration counties are home to a major university. Two of them — Harrisonburg and Virginia Tech's Montgomery County — actually lost population while ranking among the nation's top destinations for newcomers. Across the whole top thirty, the average in-migration rate is a blistering 9.2%, while the average real population growth is a yawn: 1.9%. Sixteen of those thirty grew by less than 1.5%.
It isn't only students
Universities are the loudest version of the effect, but any place built around a population that cycles through will do the same thing. The Texas list is full of counties anchored by enormous state prisons — Walker (Huntsville), Anderson (Palestine), Polk, Rusk — where inmate transfers register as in-migration the same way students do. Coryell County, home to most of the sprawling Army post at Fort Hood, posts an 8.8% in-migration rate on the back of soldiers rotating in and out on assignment.
The common thread isn't "college" — it's churn. Students, soldiers, and inmates all move in by the thousands and move out by the thousands, and gross in-migration only ever shows you the front door.
And it tells you nothing about the forecast either
Here's the part that should retire the in-migration ranking for good. We checked whether a county's in-migration rate predicts its Boom Town Index score — our model's five-year forecast for home-price growth. It doesn't. Bucket every county by how fast it's taking in newcomers and the average forecast barely moves:
| In-migration rate | Counties | Avg BTI forecast | Avg pop. growth |
|---|---|---|---|
| Under 3% | 381 | 53.1 | +0.5% |
| 3% – 5% | 447 | 50.6 | +0.9% |
| 5% – 8% | 151 | 41.1 | +1.4% |
| 8% and up | 21 | 48.2 | +1.7% |
That column of forecast scores is essentially flat — it wanders between 41 and 53 with no real direction. If anything, the highest-inflow band scores slightly below the slowest one. The model never sees migration data at all; it reads prices, rents, wages, jobs, and building permits. The point is that a number people treat as a growth signal turns out to be statistical noise next to an actual forecast.
You can watch it scatter at the county level. Isabella, Michigan and Payne, Oklahoma are churning college towns that the model loves anyway — both score above 90, on the strength of cheap homes with room to run. Hays County, Texas churns just as hard and scores a 2, because San Marcos sits in an already-expensive Austin orbit with little price headroom left. Same in-migration story, opposite forecasts. The newcomer count explains neither.
Where people actually pile up
So which counties are genuinely filling up? Flip the sort to net population growth and a different map appears — exurban Sun Belt, not college towns:
| County | What it is | In-migration rate | Actual pop. growth |
|---|---|---|---|
| Kaufman, TX | Dallas exurb | 9.0% | +7.4% |
| Rockwall, TX | Dallas exurb | 6.3% | +5.7% |
| Comal, TX | San Antonio–Austin | 6.0% | +5.3% |
| Jackson, GA | Atlanta exurb | 7.5% | +5.1% |
| St. Johns, FL | Jacksonville suburb | 3.9% | +5.0% |
Notice these don't even top the in-migration chart — their inflow rates are middling. What separates them is that the people who arrive mostly stay, so a 4-to-9% inflow converts into 5-to-7% net growth instead of evaporating. That's the difference between a turnstile and a front door that only swings one way. (Worth a caveat: a fast-growing exurb and a strong home-price forecast aren't the same thing either — several of these already-pricey suburbs score low on our model for the same headroom reason, which is its own arbitrage story.)
What to read instead
None of this means in-migration is useless — it means it's one ingredient, and a noisy one, dressed up as a verdict. If you're sizing up a place to move and a ranking tells you it's a top newcomer destination, run three quick checks before you believe it:
- Is the population actually rising? Pull net population change, not just the inflow rate. A wide gap between them is the turnstile signature.
- Who's the newcomer? A county anchored by a giant university, military base, or prison will always look like a magnet. That can be a perfectly good place to live — just don't mistake the churn for momentum.
- What does the forecast say? Durable growth shows up in prices, jobs, and permits long before it shows up in a glossy "fastest-growing" headline. We built a whole post on the permit data that front-runs the boom, and another on the signs a hot county has already peaked.
The bucket looks impressive when you only watch the water going in. Stand to the side and check the level — that's the whole trick.