The change from horses to motor vehicles caused structural and social changes. The middle class, and even the poor, could now afford personal vehicles.
Previously people threw their garbage in the street. The army of street sweepers employed by the city to pick up horse manure shifted to the garbage hauling business. People now had to use garbage cans—which weren't common.
Vehicles were more numerous and faster leading to a sharp increase in accidents and fatalities. This led in turn to licensing of drivers. Drunken driving became an issue. A drunk could tumble into a buggy and the horse would take him home. Autos crashed.
Autos got stolen and stripped, while horses returned home. For example, in 1916 there were 46,662 horse-drawn vehicles and 65,651 automobiles. According to the Police Annual Reports, 1,215 horses strayed or were stolen that year. All except 26 were recovered. Of the 3,295 automobiles which were lost or stolen, only 2,336 were recovered, leaving 959 missing.
Snow removal and street paving became issues. Motorists preferred smooth asphalt or concrete. Brick or stone provided better footing for horses. Suburbanization started with the horse railways, but accelerated with the electric street car and automobile. Traffic congestion shifted to the previously empty outlying streets. Parking became the issue that has never been solved. Paul Barrett discusses many of these topics in his classic Mass Transit, the Automobile and Public Policy in Chicago, 1900-1930.
Municipal expenditures on roads increased. As explained in Property Rules, property owners historically paid for improvements to their street. This could no longer be justified when improvements just meant more strangers speeding by.
Children could no longer play in the streets. Boulevards, such as Lake Shore Drive, were built by the parks to be pleasureways—a sort of linear park with freight traffic banned. Now boulevards became high speed express routes and the Park District was in the auto business.
On the other hand, Edith Abbott comments in the 1930s on how the change to automobiles resulted in wider and cleaner streets. This was true even in the tenement districts where few people owned autos.