The number that undoes the "America is overbuilt" argument is 60%. That is the share of the decline in for-sale inventory across the top 50 metro areas that net migration flows between July 2020 and June 2021 alone can explain. The housing debate keeps getting fought at the national level, where 142 million housing units against roughly 130 million households looks like slack. But housing does not clear nationally. It clears at the metro level, and the metros that absorbed the pandemic migration wave have been drained of supply in a way the aggregate figure conceals entirely.
This is Part 2 of our work on U.S. housing. Part 1 established that employment growth in a metro area, measured against 2019, was the dominant driver of that area's relative housing shortage, with an r-squared of 0.47. Jobs came back faster in some cities, and where they did, available homes disappeared. That left an obvious question: what moved the jobs? The answer is that people moved, and they moved for reasons that have very little to do with the models most housing analysts run.
The Fallacy of the National Number
Start with why the top-line count is misleading. Net migration within the United States does not create new housing demand in aggregate; it relocates it. If fifty people occupy fifty homes in one state and twenty-five people occupy twenty-five in another, the country is in equilibrium. When twenty-five of those first-state residents move, the national tally of seventy-five homes for seventy-five people is unchanged and useless. The receiving state now needs twenty-five units it does not have, and the sending state is left with vacancies it cannot export. Demand shifted geographically. Supply, which takes years to build and cannot be trucked across a state line, did not follow.
That is the whole game. The overbuilt-nation thesis treats housing as fungible across geography. It is not. And the migration that reshuffled demand during the pandemic was unusually large and unusually concentrated, which is why the metro-level inventory damage was severe even as the national number sat still.
What Actually Moved People
Here the analysis departs from the standard drivers. Taxes, weather, and housing affordability all matter at the margin, and affordability is becoming more decisive over time. But the sharpest signal in the 2020 to 2021 data is political. State and municipal COVID responses were adopted and perceived along party lines, and the severity of restrictions tracks the migration flows with uncomfortable precision. Across the twenty most populous states, restriction severity explains roughly half the variance in domestic migration. The more restrictive the state, the larger the net outflow.
We are calibrated on this: the relationship is a strong correlation across a single unusual year, not a proven durable law. Weather and cost-of-living have driven Sun Belt inflows for decades, and 2020 to 2021 partly accelerated trends already in motion, such as the long Northeast outflow and the steady Southern inflow. The restriction variable may be capturing preferences that were shifting anyway.
But one regional reversal is hard to explain away. The West region saw net inflows in the year before COVID, July 2019 through June 2020, and then a large net outflow in the year restrictions were in place, June 2020 through July 2021. A decades-long trend did not merely slow. It flipped. That kind of turn inside twelve months is not the signature of taxes or climate, which move slowly. It is the signature of a shock, and the timing points at the policy response.
The Wave Behind the Shortage
The migration story explains where supply was depleted. It does not, on its own, justify building at scale, because relocation is a redistribution of existing demand. The reason this matters for construction is what was arriving behind the migration: a demographic wave of first-time buyers.
The critical point about sequencing is that the inventory depletion happened first. The pandemic reshuffle drained for-sale supply in the receiving metros ahead of the largest cohort of prime first-time homebuyers reaching peak buying age in years. That is a supply-then-demand ordering, and it is the ordering that produces sustained price pressure rather than a one-off spike. A market can absorb a demand surge if inventory is ample. It cannot absorb one when the shelves were already cleared by migration the year before.
Recent search behavior suggests the geographic churn has not exhausted itself. In the first quarter of 2022, a record 32.3% of Redfin users were searching for homes outside their current metro area, per Redfin. If that intent converts at anything near historical rates, the receiving metros face continued inflow layered on top of the demographic demand, against inventory that never recovered.
Where the Thesis Breaks
The read is straightforward: the shortage is local, employment- and migration-driven, and about to meet a first-time-buyer cohort in metros that are already short. The market prices this as a national surplus. That is the mispricing.
The counterargument that would break it is a reversal in the migration engine itself. The restriction variable was a 2020 to 2021 phenomenon. With those policies now gone in nearly every state, the specific push factor has largely dissolved. If migration normalizes toward its slow pre-COVID Sun Belt drift, the acute depletion becomes a stock problem that builders can chip away at over several years rather than an accelerating squeeze. The Redfin search intent is the tell to watch here: intent is not a signed deed, and cross-metro search has historically overstated actual moves. If that 32.3% figure fades back toward its long-run range through 2022 and beyond, the demand-shift leg of the argument weakens materially.
The second break is rates. This work was framed against a lower-rate backdrop, and a sharp rise in mortgage costs suppresses transaction volume regardless of underlying demographic demand. High rates do not build the missing homes, but they can freeze the market that would otherwise reveal the shortage in price, delaying the reckoning.
The Condition That Confirms It
The observable that decides this is metro-level for-sale inventory in the top migration-receiving areas over the next several quarters. If inventory in those metros stays depressed while first-time-buyer formation climbs, the shortage is structural and the national surplus is confirmed noise. If inventory rebuilds meaningfully as migration cools and construction responds, the squeeze was cyclical and the overbuilt camp gets its vindication late.
Part 3 takes up the quantity itself: how many new units the receiving metros actually need to satisfy the expected demand over the next few years. The migration and demographic evidence here sets the direction. The build estimate sets the size.
