Lake Street #5 Near Engine House at Crawford
Before electrification, the first two 'L' roads ran trains with wooden cars pulled by steam locomotives like this one here. These locomotives burned coal to heat water and create pressurized steam like any steam engine would, but were much smaller than what you might have seen in old movie footage of intercity railways. 'L' trains were light and the locomotives needed to be, too, so they could pick up speed and stop quickly, considering the close spacing of rapid transit stations.
The locomotive style is called a "Forney," after steam locomotive designer Matthias Forney, which could operate in either direction, helping to make it easier to attach a locomotive to the back side of a train at the end of a line, and change direction and run a reverse trip without having to turn a locomotive around.
The Lake Street 'L' actually named its locomotives in addition to numbering them. Seen here is #5, named "Lizzie A." (unfortunately, we're not sure who Lizzie was, but she probably was someone who had a relation to the 'L' company or someone else who did). The Lake Street 'L' ran steam locomotives until 1896, converting to electric power a little ahead of its slightly older peer serving the South Side, a separate company at the time.
The station in the background is Crawford, later renamed Pulaski.