By the late 1920s, street lights were extended further over the streets to provide better light for automobile travel. Brackets and arms were attached to posts. These curved brackets with lantern-like light fixtures generally date to the late 1920s and early 1930s. The lanterns hark back to the gas light fixtures of the 19th century.
The earliest sodium vapor lighting was introduced at the Chicago World's Fair of 1933-1934. Before becoming widespread, the lighting fixtures took on the characteristics of other 1930s curved bracket fixtures. They are characterized, though, by the light fixture, seen in the image below.