Multifamily Submarket Drivers: Demographics and Migration

Introduction

The first-order question in multifamily diligence is not the property; it is the submarket around it, and that call comes ahead of the property tour. Hold the operator, the vintage, the building class, the renovation budget, and the leverage constant, and two assets in different submarkets can still post NOI growth several hundred basis points apart in a single year. Properties bought in submarkets with positive job growth, net in-migration, and a supply pipeline the market can absorb compound NOI faster than properties bought in submarkets without those fundamentals, and the spread between a right-submarket and wrong-submarket acquisition in the same cycle routinely exceeds the spread from any other lever an institutional buyer controls.

The demand side of that call runs on four levers, and they are not interchangeable. Job growth creates new households that need housing where the jobs are. In-migration imports households into a submarket without requiring any local household to form. Household formation captures the demographic transitions (a millennial leaving a roommate situation, a Boomer downsizing) that create rental demand independent of who is moving into the metro. And the affordability gap between renting and owning decides how much of all that demand lands in apartments rather than for-sale housing. Each is separately measurable through a mix of public data (the Bureau of Labor Statistics for employment, Census ACS and IRS county-to-county files for migration) and proprietary platforms (CoStar, RealPage, Yardi), and the analyst's job is to combine them into one demand-side view, then test it against supply. The same demand-versus-supply discipline runs through the broader US multifamily sector; here it is applied one submarket at a time.

Multifamily Submarket

A geographic subdivision of a metro market that institutional analysts use as the operational unit for multifamily underwriting. Submarkets are typically defined by neighborhood boundaries, school district lines, or natural geographic divisions; they range from large submarkets (suburban areas of 50,000+ rental units) to small submarkets (urban neighborhoods of 5,000-10,000 rental units). Submarket definitions vary across data providers (CoStar, RealPage, Yardi) but generally align within each metro. Institutional underwriting always works at the submarket level rather than the metro level because submarket fundamentals can vary meaningfully within the same metro (different submarkets of Dallas-Fort Worth often have meaningfully different supply pipelines, demographic mixes, and rent trajectories).

Job growth sits upstream of the other three drivers because new payroll positions are what generate the household formation and in-migration that ultimately rent apartments. Across the major multifamily metros the 2025 picture showed real dispersion: Phoenix around 2.0%, Austin near 1.8%, Charlotte at the high end of the range on a professional-and-business-services rebound, Dallas-Fort Worth solid on continued California relocations, and the coastal gateways (New York, Boston, San Francisco) at the low end with roughly 1.0-1.5% growth off their mature employment bases.

Analysts convert that growth into unit demand with a rule of thumb of roughly 0.4 to 0.6 multifamily units demanded per net new job, varying with how renter-heavy the metro is. Phoenix's 2.0% growth on an employment base near 2.4 million implies on the order of 48,000 new jobs a year and, applying the ratio, somewhere around 20,000 units of net new apartment demand. The point of the calculation is never the precise figure; it is to set a demand number that the next step, the supply pipeline, gets measured against.

In-migration into the Sun Belt has been the defining demographic story of US multifamily for more than a decade, and the 2024-2025 data shows it continuing, if at a calmer pace. On absolute net migration the South still leads, with Texas (roughly 235,000), Florida (201,000), North Carolina (131,000), and South Carolina (80,000) at the top. Strip out international flows and look only at state-to-state moves and the order shifts: North Carolina led net domestic migration (around 84,000), ahead of Texas (67,000), South Carolina (67,000), and Tennessee (42,000). On a per-capita basis the smaller states (South Carolina, Idaho, North Carolina) screen even better. That concentration shows up in metros like Dallas-Fort Worth, Austin, Houston, Charlotte, Raleigh-Durham, Tampa, Orlando, Jacksonville, Charleston, and Nashville, with secondary magnets like Myrtle Beach, Knoxville, Boise, and Colorado Springs picking up flow.

What changed is the magnitude. The 2021-2022 pandemic spikes have given way to slower but still-positive net domestic migration, a slowdown sharp enough that some analysts call it a stall. The cooling bites hardest in the high-supply metros (Austin, Phoenix, Nashville), where a record delivery wave is meeting demand that has come off its peak. Submarkets still drawing strong in-migration against a constrained pipeline (Charlotte, Raleigh-Durham, parts of Florida) are the ones set up for firmer near-term rent growth.

The third demand driver, household formation, captures the demographic transitions that create new rental demand independently of metro-level migration. Two cohorts drive most of the institutional multifamily demand picture:

The two cohorts pull toward different product. Millennials cluster in urban mid- and high-rise apartments near employment centers; Boomers gravitate to suburban garden-style communities near amenities, healthcare, and family. Submarkets that can capture both (suburban nodes with a real job base and lifestyle amenities) tend to outperform submarkets that serve only one cohort, which is part of why the Class A, B, and C distinction interacts so tightly with submarket selection: the same demographic tailwind lands very differently on a new Class A high-rise than on a 1980s Class B garden complex two miles away.

Net Domestic Migration

The net flow of US residents into a state or metro from other US locations, measured as inbound moves minus outbound moves over a defined period. Distinct from international migration (cross-border immigration), which is tracked separately. Net domestic migration is the primary driver of metro-level population change in the absence of large international flows; for US multifamily underwriting, the metric is typically tracked at the state level (via IRS migration data and Census ACS) and at the metro level (via private data providers like Go Mini's, U-Haul, and Atlas Van Lines). On a domestic basis the 2024-2025 leaders were North Carolina, Texas, South Carolina, and Tennessee.

The fourth driver, the gap between renting and owning, has been the dominant macro story for multifamily demand since mortgage rates spiked in 2022. The rough math still favors renting even after rates eased from near 7% to about 6.1% over the past year. The income needed to afford a median-priced home runs above $110,000, against a median household income near $86,000, while the income needed to afford the typical asking rent of about $1,900 a month sits around $76,000. On a monthly basis the median mortgage payment on a purchase application is roughly $2,025, versus a Census-style median gross rent near $1,500. The lower rates have trimmed a typical mortgage payment by something like $125 a month, so the gap is narrowing, but it has not closed, and home prices, not rates, are the binding constraint: home-buying volume is sitting near 30-year lows. Marginal households keep extending their rental tenure rather than buying.

The gap is widest in high-home-price metros (San Francisco, Los Angeles, Seattle, Boston, New York, Washington DC), where the rent-versus-own math heavily favors renting, and narrower in lower-price Sun Belt metros where ownership stays within reach even at current rates. That geography is one reason coastal multifamily has held up reasonably well through 2024-2025 despite slower in-migration and job growth: the affordability pull into rental has offset thinner demographic tailwinds.

The four drivers describe demand. The other half of the submarket call is supply, meaning the multi-year delivery pipeline stacked on top of existing stock, and the two have to be read together because demand alone predicts almost nothing about near-term rent growth. A submarket with strong demand but a heavy pipeline (Austin, Nashville, and parts of Phoenix through 2024-2025) posts weak or negative same-store NOI growth in the near term despite a sound long-run thesis, while a submarket with only modest demand but a starved pipeline (older urban pockets in coastal markets, mature Midwest suburbs) can deliver firmer rent growth simply because nothing new is competing for the tenant.

This is why the same metro can be a buy and a sell in the same year depending on which submarket and which vintage of pipeline. It also explains why submarket diligence does not end the underwrite; once the submarket call is made, the work moves down to the asset, where comparable sales analysis prices the specific property against recent trades. The submarket view tells the analyst whether the demand curve is moving toward the asset or away from it; the supply pipeline tells them when. Get both right and the property-level execution has a tailwind to work with; get the submarket wrong and no amount of capex or operational discipline fully compensates.