While exploring the history of street trees, I came upon a law passed by the United States Congress on April 6, 1870, authorizing the city of Washington, D.C., to set aside up to 50 per- cent of the width of a street for the creation of “parks for trees and walks.” At that time, the Senate debated about the proper layout of the street, whether to have “the parking on either side of the street and the roadway in the cen- ter” or to have the “parking” in the center of the street. According to the 41st Congress, the proper way to park in cities was on the side of the streets with the roadway running down the center. Of course, in 1870 the members of the Senate were discussing the parking of trees and smaller plants, not automobiles. The first parking system was an early street tree system where parking defined the planting of trees, grasses, and flowers along the side of roadways and the creation of sidewalks for pedestrians.
From The Etymology of Parking by Michele Richmond