there were street cars left over in many cities after the horse drawn cars were made obsolete by the change to electric streetcars

One ingenious landlord of Seattle, supplied summer cottages at the beaches, and solved the problem of low rents by buying worn-out street cars from the local transportation company and converting them into bungalows.

One car makes a very comfortable cottage, while two joined together with a basement beneath make a residence, which, under the circumstances, may be regarded as spacious.

http://www.carville-book.com/bonus.php

One amusing solution to meeting the pressing housing needs after the 1906 earthquake and fire was provided by Dr. Charles V. Cross living at 2808 California street at Fifth Avenue in the Richmond District. Mimicking the Carville community of the Outer Sunset district, Cross lined up ten old McAllister line cable cars and created the "Carzonia apartments" on his property along the narrow strip separating California and Cornwall streets. The doctor had a fellow physician, Dr. S. Ward Moss, act as architect to add plumbing and electricity.

http://www.outsidelands.org/carzonia.php

In 1945 some of the old street cars were still laying around unused