An article from Governing Magazine which is a summary of tent cities that have become somewhat permanent.
Like many other metro areas in the mid-2000s, Seattle’s King County set out to end homelessness within 10 years. Far less common, though, was a policy enacted in Seattle to permit homeless encampments, also known as tent cities, to deal with limited shelter capacity. After a decade, homelessness hasn’t gone away completely, and neither have the tent cities. If anything, they’re becoming more permanent.
Homeless encampments in the U.S. are at least as old as the Great Depression, when Seattle and other American cities saw the rise of so-called “Hoovervilles.” Encampments again started sprouting up in King County in the 1990s, but officials worked to convince camp organizers to shut them down in exchange for shelter elsewhere. But when King County was planning its blueprint to end homelessness around 2004, a local coalition pushed to formalize a permitting process for encampments that made them temporary, limited their residents, required sponsorship by an outside organization and regulated conduct within camps. The county largely adopted those recommendations. In late 2014, it agreed to extend them for another decade.
At least five King County camps now have legal status. Homeless encampments are hardly isolated to Seattle, though the area is among only a handful of places that formally recognize them. Another 10 or so camps across the U.S. fall into “semi-sanctioned” status, the equivalent of local officials looking the other way or providing at least some support, according to a report last year from the National Law Center on Homelessness and Poverty. The report found at least 100 nonsanctioned encampments in existence across the U.S., though there are likely more.
Retrieved February 23, 2015 from http://www.governing.com/topics/health-human-services/gov-tent-cities-seattle.html