The current housing recovery may be like manna to homeowners, but it may do little to ease a growing shortage of affordable residences, and could even make it worse. After a recession-generated drought, household formation is on the rise, notes a recent study by the Harvard Joint Center on Housing Studies, and in many markets there isn’t an adequate supply of housing for the working and middle classes.

Given problems with regulations in some states, particularly restrictions on new single-family home development, the uptick in housing prices threatens both prospective owners and renters, forcing people who would otherwise buy into the rental market. Ownership levels continue to drop, most notably for minorities, particularly African Americans. Last year, according to the Harvard study, the number of renters in the U.S. rose by a million, accompanied by a net loss of 161,000 homeowners.

This is bad news not only for middle-income Americans but even more so for the poor and renters. The number of renters now paying upward of 50% of their income for housing has risen by 2.5 million since the recession and 6.7 million over the decade. Roughly one in four renters, notes Harvard, are now in this perilous situation. The number of poor renters is growing, but the supply of new affordable housing has dropped over the past year.

So while the housing recovery — and the prospect of higher prices — does offer some relief to existing homeowners, it’s having a negative impact further down the economic ladder. For the poorest Americans, nearly eight decades of extensive public subsidies have failed to solve their housing crisis. Given the financial straits of most American cities — particularly those like Detroit that need it the most — it’s unlikely the government can rescue households stressed by the cost of shelter.

As one might suspect, the problem is greatest in New York, New Jersey and California, say the Harvard researchers .In those three states 22% of households are paying more than 50% of pre-tax income for housing, while median home values and rents in these states are among the highest in the country. According to the Center for Housing Policy and National Housing Conference, 39% of working households in the Los Angeles metropolitan area spend more than half their income on housing, 35% in the San Francisco metro area and 31% in the New York area. All of these figures are much higher than the national rate of 24%, which itself is far from tolerable.

Other, poorer cities also suffer high rates of housing poverty not because they are so expensive but because their economies are bad. In the most distressed neighborhoods of Baltimore, Chicago, Cleveland and Detroit, where vacancy rates top 20%, about 60% of vacant units are held off market, indicating they are in poor condition and likely a source of blight.

America’s emerging housing crisis is creating widespread hardship. This can be seen in the rise of families doubling up. Moving to flee high costs has emerged as a major trend, particularly among working-class families. For those who remain behind, it’s also a return to the kind of overcrowding we associate with early 20th century tenement living.

As was the case then, overcrowded conditions create poor outcomes for neighborhoods and, most particularly, for children. Overcrowding has been associated with negative consequences in multiple studies, including greater health problems. The lack of safe outside play areas is one contributing factor. Academic achievement was found to suffer in overcrowded conditions in studies by American and French researchers. Another study found a higher rate of psychological problems among children living in overcrowded housing.

America’s Emerging Housing Crisis – Forbes.