Frequencies weren't fully standardized, either. Although 60Hz AC had become very common in most of North America by 1900 or so, many urban centers already had DC service and would continue to have it until well into the '30s. And most of Southern California had 50Hz AC service until the late '30s.
Britain had a similar variety of frequencies in the early days, finally standardizing on 50Hz with the construction of the National Grid.
D.C. supplies (3-wire, 200/400 to 250/500V) were still in use here in the older districts of some towns well into the 1950s.
