Velvety green lawns are a recent phenomenon in United States history. 'Lawn' was not even a commonplace word in America until after the Civil War. Houses in northern towns were built close to the street, often with a small fenced-in flower garden in front. Most had packed-dirt yards or native plants that flourished or failed with rain and drought. 'Swept yards' of sand or dirt were common in the South. Wealthy landowners began to copy England's aristocratic estates in the late 1860s. The lawn became a middle-class ideal in the new suburbs, made possible by commuter trains, trolley cars, and the introduction of a popular hand-pushed lawn mower in 1870. By the mid-20th century, lawns were a fixture of American culture.
Source: 'The Lawn,' by Virginia Scott Jenkins (Smithsonian Institution Press, 1994).