Mary Anderson invented the windshield wiper in 1903 after noticing during a snowy trip to New York City that streetcar drivers had to constantly stick their heads out of the window to see where they were going.

A small sweep that changed the driver’s workload

A windshield wiper solves a problem that glass alone cannot: rain and melting snow cling to the outside surface, scattering light and blurring the road. The blade clears a narrow path by pressing against the glass and pushing water and slush aside. Its repeated back-and-forth motion matters; one pass may open a view, but precipitation begins covering it again almost at once.

Why the spring and pivot matter

The arm pivots so the blade can travel across part of the windshield rather than merely scrape one spot. A spring presses it toward the glass, helping the blade maintain contact as it moves. Too little pressure leaves wet streaks; uneven contact can leave portions of the sweep uncleared. The mechanism is simple, but it turns a visibility problem into a controlled movement at the edge of the driver’s view.

Anderson’s hand-operated design left the driver in charge of when to move the blade. That avoided relying on a motor, but it also meant the driver had to operate the control while steering and watching traffic. The essential advance was not that a blade made the windshield perfectly clear—it could not—but that clearing it no longer required the driver to expose their face to the weather.

The lasting idea is the division of labor: the driver stays protected inside, while a small mechanism repeatedly maintains a usable patch of sight through the glass.