Opponents often argue that upzoning (i.e., allowing townhouses and low-rise apartments in residential neighborhoods) will displace lower-income residents, but credible studies indicate that neighborhoods which allow more housing to be built actually experience less displacement, as discussed in this recent City Observatory column, If You Want Less Displacement, Build More Housing. As the author explained,
If you don’t build new housing, you intensify the shortage, raise the rents, and amplify the displacement. This isn’t intuitively obvious. People, unsurprisingly, associate new buildings with new residents, and simplistically assume that if new housing isn’t built, that new people won’t show up, or that they’ll simply go somewhere else. But that’s not the case.
Even if the new housing is initially too costly for lower-income households, it serves growing demand, so wealthier households do not out-bid lower-income households for available housing stock, an effect called filtering.
In the game of musical chairs that is the urban housing market, the only way to make sure that people are not displaced is to add more chairs. The research that’s been done on the subject indicates that building more market rate housing reduces displacement.