Electric lighting service for this residential neighborhood in Illinois was once provided by the lines and transformers that you see on the left. Those transformers were cast iron and quite heavy! Through the teens and thereafter distribution transformers became physically lighter with the ability to handle more load with less core loss without too much increase in size. The transformers in this photo converted primary voltage (either 1,100 or 2,200 volts) to around 110 volts secondary for their utility's customers.
An openwire telephone line is visible on the right that provided local service to this community.