By the 1840s, the gas lamp was the principal form of street lighting in the United States and remained dominant throughout the 19th century, even after the advent of electricity. These models appeared in an 1888 catalogue and represent a wide range of styles that appeared in the mid-to-late 19th century. Gas street lights generally had straight posts. Many electric lights from the 20th century were modeled after the designs of gas lamps, but notice that the gas lamp is open at the bottom to allow the lamplighter access the interior for lighting.
The appearance of a gas light in an historic image, without the presence of any electric street lights, would imply a pre-1890s date. If gas lights appear along side electric lights, particularly in commercial districts, a late-19th to early-20th century date is likely applicable. However, in many residential districts, gas lights were often not replaced until 1920s.