Gentrifying neighborhoods in Washington, D.C., Boston, New York, and elsewhere are making life more difficult for poor, large families.

Developers raze old apartment buildings, and erect in their place luxury dwellings that long-time families cannot afford. Those families must then deal with displacement. Sometimes, they have to move to other neighborhoods that may be far from support services, schools, and jobs.

There are studies that say poverty is a bigger issue for these families than is gentrification, the latter of which is fairly rare. But when developers come in, large families who are displaced are even more challenged to find apartments that meet their needs. These are families with multiple children, or families which include members of multiple generations who have moved in to share resources. The Pew Research Centerresidency rules for families who live in Section 8 housing. A family of four – depending on the gender and age of the residents – could require as many as four bedrooms, and apartments that large are rare.

Yet large poor families – multi-generational or not – are rarely a part of public policy discussions. Instead, cities tend to focus on building smaller units like studios or smaller. In New York, former Mayor Michael Bloomberg proposed a plan for multiple “micro-units” that include living spaces of just a few hundred square feet.

Housing advocates spoke up and said the plans didn’t include enough space for large families.

That’s the case nationwide. In most cities, city-financed housing are smaller units – two-bedroom apartments are the outlier.

Governing magazine recently compiled data from 25