States across the country are easing restrictions on accessory dwelling units (ADUs), fueling their use as multigenerational housing for aging parents, adult children and young families priced out of traditional homeownership. Urban and Regional Planning Professor Dohyung Kim says ADUs have long served families but were historically restricted by zoning policies that limited additional housing on residential lots, adding that many cities opposed ADUs because they were often rented to lower-income tenants.

This article was originally published by The Washington Post on July 5, 2026.