During a visit to New York City in the winter, Mary Anderson observed a streetcar driver struggling to see through the snow-covered windshield. This observation sparked the idea for a device to clear windshields, leading to her invention.

Upon returning home, Mary Anderson designed a manually operated windshield cleaning device. She hired a company to produce a working prototype. The device consisted of a lever inside the vehicle that controlled a spring-loaded rubber blade on the outside of the windshield.

Mary Anderson formally filed a patent application for her "window cleaning device for electric cars and other vehicles" with the U.S. Patent Office. This was a crucial step in securing her intellectual property rights.

The U.S. Patent Office granted Mary Anderson Patent Number 743,801 for her windshield wiper design. This gave her exclusive rights to manufacture, sell, and use the invention for a period of 17 years.

Despite the patent, Anderson faced challenges in commercializing her invention. The automotive industry was still in its early stages, and there was resistance to adopting the device. Some believed it would distract drivers, while others questioned its necessity. She tried selling the rights to a Canadian firm, but they declined.

Mary Anderson's patent expired, allowing other manufacturers to produce and sell windshield wipers without paying royalties. This coincided with the rapid growth of the automotive industry, leading to the widespread adoption of windshield wipers as standard equipment.