My city (Portland) has incentives for developers to build affordable housing - adding affordable units to a project increases the allowed density of the develop

My city (Portland) has incentives for developers to build affordable housing - adding affordable units to a project increases the allowed density of the development, allowing more total housing on the same lot, and presumably, more return for developers. Portland does still have high rents, so it’s hard to point to this as a “success”, but I think it’s a good template for how you can encourage affordable units without putting the whole city under tight rent control.