Much attention has been paid to the fact that the federal minimum wage has not kept pace with inflation (or with increases in worker productivity, or with the rising incomes of the 1 percent). But in a much less abstract sense, federal and local minimum wages have also failed to keep up with the rising cost of rent.

As a result, according to a new report from the National Low Income Housing Coalition, a minimum-wage worker in the District of Columbia – where the wage floor is currently $8.25 an hour – would need to work 137 hours a week to afford what the Department of Housing and Urban Development considers a fair market rent for a modest two-bedroom home. Put another way: A local household would need 3.4 full-time minimum-wage workers to afford such a home. Or, a single earner in that household would need to make a lot more money: $28.25 an hour to be exact.

The National Low Income Housing Coalition refers to this last statistic as a "housing wage." It's the amount of money a person would need to earn per hour to afford the local fair market rent (including utilities) for a two-bedroom home, based on a 40-hour week and a 52-week working year (yes, that assumes zero time off). This figure also assumes that a person spends no more than 30 percent of his or her income on housing. In the District, HUD's fair market two-bedroom rent is $1,469 a month, meaning a household would need to make more than $58,000 a year.

The District currently has one of the largest gaps in the country between what minimum-wage workers earn and what they'd need to make to afford such a home. Nationwide, the average housing wage is $18.92, a number that's obviously higher than the minimum wage everywhere in the country.

Here is the same map translated into hours:

A couple of points to acknowledge in looking at these maps: Not everyone needs a two-bedroom home, nor do all families that need two bedrooms have only one earner. But this scenario represents a realistic challenge for a single parent. And even fair market rent for one-bedrooms may be widely out of reach.

Also, only about 5 percent of hourly paid workers in America make the minimum wage. That said, these numbers suggest that a single parent would still struggle in much of the country on higher wages than that.