Yes, Los Angeles does have a river, it flows year round and local leaders are trying to restore it, or at least make it less like it is now, which is paved in concrete and pretty lifeless in areas. In the neighborhood where I live, the L.A. river has bike paths, trees, a natural bottom with islands. It also has a lot of homeless encampments that forces cyclists to slow down to avoid hitting the campers, their shelters and their possessions.
On the back, "IRA SWETT---Standard Collection" I found a bit about Swett. He was born in L.A. in 1913 and died, also in Los Angeles, in 1975. I couldn't find any evidence that he ever worked for a railroad or interurban company, but I did find plenty of proof of his love of light rail. He was the author of a number of booklets and news letters about L.A. area traction companies, and a few things about transit in Seattle. He was stationed there during World War 2. Basically, he was born at the height of interurban transportation in Los Angeles and lived to see it die. Since Swett's death L.A. county has added a number of new light rail lines and a subway, with a number of extensions are being built.
Also stamped on the back, "J737" A best guess, either June or July 7, 1937. The Los Angeles River was paved in 1938. I don't know exactly where this picture was taken, but the large building in the background is a hospital that's still there.
