Eli Whitney invented the cotton gin in 1793. The cotton gin efficiently separated cotton fibers from seeds, revolutionizing the cotton industry and greatly increasing demand for slave labor. Whitney struggled for over a year to construct a full-sized working cotton gin after submitting a small model. He received a patent for the cotton gin on March 14, 1794. In addition to the cotton gin, Whitney invented interchangeable parts and prototype gunlocks and helped pioneer mass production techniques.