Imagine living in less than 400 square feet of space, and paying top dollar for the privilege.

While hard to believe, its becoming the norm for renters in cities across the country such as Boston, Seattle and Washington, D.C. In key metropolitan markets, those places certainly dont come cheap: In San Francisco, rent can run as high as $1,700 a month.

According to the Citizens Housing and Planning Council, several cities such as Atlanta, Cincinnati and Pittsburgh are also seeing singles make up close to half of their households. That will likely put a strain on apartment rents, and could lead to the proliferation of more micro apartment projects.

Read more in CNBC.