Building more high-end apartments doesn’t sound like quick fix for the affordable housing crisis. But maybe you just have to look harder.
The pro-market-rate position, championed by YIMBYs, is more optimistic: This view would concede that, though it’s true that new market-rate units will be expensive given the current scarcity of housing, new units will ease up demand for existing housing. Through a process known as filtering, this older housing gradually becomes more affordable to middle- and low-income households. This will ultimately mitigate displacement risk in more vulnerable communities.
The first round of moves are roughly what you might expect: Approximately 70 percent came from nearby neighborhoods with above-average incomes, with the remaining 30 percent moving from below-average neighborhoods. These aren’t exactly inspiring results for activists focused on helping households at the bottom of the market.
But when a household moves into a new unit, they initiate a kind of housing musical chairs by vacating their existing unit. A second household then moves into that unit, in turn vacating a third unit. For each new market-rate building, Mast follows this trail of movers back through six moves, tracking where residents are moving from, a process he calls the migration chain.
By the sixth link of this chain, Mast finds that approximately half of the movers are moving out of census tracts with below-median incomes. As many as 20 percent of movers are coming from the poorest tracts in the city.
These findings suggest that housing markets aren’t nearly as segregated as some might fear, if you work your way down the migration chain far enough.
His model suggests that for every 100 luxury units built in wealthier neighborhoods, as many as 48 households in moderate-income neighborhoods are able to move into housing that better suits their needs, vacating an existing unit in the process. Somewhere between 10 and 20 of these households are coming from among the city’s lowest-income neighborhoods, vacating units and reducing demand where housing is most likely to be affordable for working families.