One of the most famous African-American inventors was Elijah McCoy, whose railroad invention came to be in such demand that it spawned a phrase still familiar to people today.

One of 12 children of a pair of runaway slaves who traveled the Underground Railroad, Elijah McCoy was born in 1844 in Ontario, Canada. He lived there for a time, and the family then moved back to the United States, settling in Michigan. When Elijah was 15, his parents sent him to Scotland to study; he became very knowledgeable and proficient in mechanical engineering.

After he returned, he found a job as a fireman and oiler for the Michigan Central Railway. It was doing this work that gave him the idea for his most famous invention. Train engines at the time couldn't go far before having to be stopped in order to oil the engine parts; this oiling of the parts had to be done by hand as well, making it even more time-consuming. McCoy had the idea to invent a device that would enable the oil to spread over the engine parts while the train was still moving. The Automatic Lubricator, or Lubricating Cup, would eventually fill up and have to be emptied, but not before the train had gone well down the track. This improved rail travel times a great deal.

McCoy received a patent for his Automatic Lubricator in 1872. Other inventors came up with very similar devices, but McCoy's device proved superior to its competitors, so much so that railroad company equipment buyers would ask for McCoy's invention by name. They would say that they wanted "the real McCoy"–a phrase that is still in use today, as is his invention, in other transport systems.

McCoy and Elizabeth Stewart were married in 1868; she died in 1872. His second wife was Mary Delancey; they married in 1873, and she died in 1923.

McCoy went on to invent other very useful things, including a lubricator for air pump brakes and a steam dome for locomotives. In all, before he died in 1929, he had been granted nearly 50 patents. His inventions in later years were more of the household variety, including a folding ironing table (his second wife's idea), an improved lawn sprinkler, and even something as pedestrian as an improved rubber heel to use in shoes.