On August 11, 1896, Harvey Hubbell received U.S. Patent No. 565,541, on a Socket for Incandescent Lamps — the first lamp socket with a pull cord:

Harvey Hubbell was born in Connecticut in 1857. A prolific inventor, Hubbell received at least 45 patents, primarily relating to electric products. He is best know for the pull-chain electrical light socket (above), and most famously the separable electrical power plug, which he patented in 1904 (U.S. Patent Nos. 774,250, and 774,251), the ‘251 patent showing the familiar two flat prongs, but arranged in planar, rather than parallel, configuration.

Nine years later, Hubbell patented the parallel prong plug (U.S. Patent No. 1,064,833):

and 4 years after that the polarized version of the plug, with one prong slightly larger than the other (U.S. Patent No. 1,180,638):

Hubbell founded Hubbell Incorporated in Bridgeport, Connecticut, which is still in business today, headquartered in Shelton, Connecticut.