Bankrate.com, a mortgage info site, published a very extensive article about cohousing:
Cohousing creates communities by design
Believing that no barriers are needed between good neighbors, in 1986, a pair of homeowners on N Street in Davis, Calif., tore down the fence separating their tract homes to create a common backyard.
Within two years, the shared yard encompassed four properties and Kevin Wolf and his neighbors “were doing potlucks together.”
N Street Cohousing is featured prominently as are Manzanita Village, and Bartimaeus Cohousing.