Not much traffic other than the streetcars in this early photo of Milwaukee, Wisconsin. Milwaukee had electric streetcars starting in 1890. They operated until 1958. Milwaukee also had interurbans that connected the city with Kenosha, East Troy/Burlington, Watertown, and Sheboygan. The interurban trains had all been replaced with buses by 1947.
This card dates from about 1907. If you're specifically interested in streetcars of Wisconsin, you should check out the Transport Co. Web Station website.