In the early years of U.S. history the only roads were in and around cities and well settled regions along the Eastern seaboard. Transportation of goods and people largely relied on water routes, over the ocean or along interior rivers. The vast interior of the land was reachable only by rivers, or on foot or horseback.
One problem river navigation suffered was that the boats could easily become stuck on sand bars, and would require much pulling and digging to free them. A country lawyer named Abraham Lincoln traveled extensively by river boat, and observed many a stranding. He came up with a device which would raise a stranded boat in the water, thus allowing it to be pulled off a sand bar.
He later became President of the United States. He remains the only U.S. President to receive a U.S. patent, although Thomas Jefferson invented several items worthy of patents, including an improved plow. There was no patent system in place at the time of Jefferson's inventions.