Built in the 1870s, New York City’s elevated railway had a significant problem – the sound of the trains running along the tracks was so unbearably loud that New Yorkers couldn’t live near the tracks. Realizing they needed a solution – quickly – the city government commissioned several scientists, including Thomas Edison, to invent a noise dampening system.
Unfortunately, none of the scientists could figure out a solution. Even Edison, who spent six months working on the project, could not develop a noise dampening system.
Finally, frustrated with the noise levels and lack of progress, Mary Walton, who owned a boarding house on 12th Street and 6th Avenue next to one of the train tracks, set to work finding her own solution.
After building a model railroad in her basement to experiment with ways to muffle the excessive sound, Walton realized the noise problem came from the wooden rail ties. She created a cotton- and sand-filled box that fit between pairs of ties and was sealed in place with tar. After being granted patent #327,422 in February 1881 for her solution, she sold her patent to the New York City Metropolitan Railroad for $10,000 and royalties. The system was such a success that it was quickly used by other railroad companies across the country.
Walton was considered a hero, especially for women, as the male engineers and inventors hired by the government hadn’t been able to solve the problem.
Unfortunately, even with Walton’s sound dampening boxes, the elevated trains were still louder than the underground subways. As time passed, they became outdated and increasingly unsafe. The trains eventually stopped running in the 1930s as infrastructure improvements became more expensive and real estate developers campaigned for their removal to replace the tracks with more desirable (and expensive) properties. Manhattan reverted to the underground subway system still in use today, though a few subway lines in the city’s other boroughs still run on elevated tracks.