Lincoln Logs is a U.S. children's toy consisting of notched miniature logs, used to build small forts and buildings. They were invented by John Lloyd Wright, second son of the architect Frank Lloyd Wright. Lincoln Logs were inducted into the National Toy Hall of Fame in 1999. As of 2014 Lincoln Logs are manufactured by K'NEX Industries Inc.
The logs measure three quarters of an inch (roughly two centimetres) in diameter. Analogous to real logs used in a log cabin, Lincoln Logs are notched so that logs may be laid at right angles to each other to form rectangles resembling buildings. Additional parts of the toy set include roofs, chimneys, windows and doors, which bring a realistic appearance to the final creation. Later sets included animals and human figures the same scale as the buildings.
The toy sets were originally made of redwood, with varying colors of roof pieces. In the 1970s the company unsuccessfully introduced sets made entirely of plastic, but soon reverted to real wood.
Lincoln Logs were invented sometime around 1916–1917 when John Lloyd Wright was working in Japan with his father. The mold for the toy was based on the architecture of the Imperial Hotel in Tokyo, designed by the inventor's father. The foundation of the hotel was designed with interlocking log beams, which made the structure "earthquake-proof".
When he returned to the US, John organized The Red Square Toy Company (named after his father's famous symbol), and marketed the toy in 1918. Wright was issued U.S. patent 1,351,086 on August 31, 1920, for a "Toy-Cabin Construction". Soon after, he changed the name to J. L. Wright Manufacturing. The original Lincoln Log set came with instructions on how to build Uncle Tom's Cabin as well as Abraham Lincoln's cabin. Subsequent sets were larger and more elaborate. The toy was a hit, following as it did Meccano, Tinker Toys and Erector Set introduced a few years before.