The Elisha Gray House in the Hazel Avenue/Prospect Avenue Historic District in Highland Park, IL (c. 1870). By some accounts, the telephone was invented here in 1874. Gray was born in 1835 in Ohio and studied at Oberlin College. Though he never graduated, he gained a lot of experience working with electrical devices and taught some classes there on the matter. He also built equipment for the Oberlin faculty. In 1865, Gray invented a telegraph relay that could automatically adapt to the insulation of the telegraph line. With this invention (and his others) in high demand, Gray founded the Gray & Barton Co. in Cleveland to supply telegraph equipment to Western Union. While his partners focused on providing for the company, Gray became more interested in the idea of an acoustic telegraph. An acoustic telegraph would allow multiple messages to be transmitted over the same lines. In 1872, Western Union purchased one-third of Gray and Barton & Co., renaming it to Western Electric. Two years later, Gray retired to focus on his own projects. Later in 1874, he invented one of the first electric musical instruments. In 1875, he was granted a patent for his acoustic telegraphy device.

Gray's place in history is inextricably linked to that of Alexander Graham Bell. Gray had been quietly working on a new invention for transmitting voice sounds. He filed a patent caveat with the US Patent Office on February 14, 1876, the exact same day that Alexander Graham Bell independently filed his own patent application. Bell's lawyers had been tipped off about Gray's application, and before they submitted Bell's design, they added a few sentences to Bell's patent copied from Gray's work. Gray's patent reached the patent office first, but Bell's lawyers wisely pressed the patent office to read Bell's design first. Bell, in the meantime, was completely oblivious to the fact that his design patent had been submitted. The plagarism in Bell's submission was noticed, and the patent was returned to Bell, with instructions to return the application in 90 days to amend his claims. Bell's lawyers found that Bell had submitted a somewhat similar idea a year earlier where mercury was used in a circuit breaker. They amended Bell's application to state that Bell should have credit for Gray's liquid microphone. On March 3, 1876, the US Patent Office sided with Bell. Bell adopted Gray's ideas about a liquid transmitter in future telephone designs, becoming the first to show proof of concept. Gray sued Bell, but after two years of litigation, the courts sided with Bell.

Gray invented a telautograph in 1887, a device that could transmit handwriting through telegraphs. The device was popular with banks and military for its ability to transmit signed orders over long distances. This was the precursor to the fax machine. Late in his career, Gray toyed with what he called the telephote, a closed-circuit television system. In 1899, he successfully developed a method to communicate underwater, a very valuable system for the Navy. He died in 1901. The house itself was one of the few remaining houses built by the Highland Park Building Company.

This is an image of a place or building that is listed on the National Register of Historic Places in the United States of America. Its reference number is 82002563.