In April 1831, on a flatboat grounded on the Rutledge milldam below the town of New Salem, Abraham Lincoln worked to pry the boat loose, directed the crew, and ran into the village to borrow an augur to bore a hole in the end hanging over the dam, causing the water to drain and the boat to float free. Seventeen years later, while traveling home from a round of political speeches, Lincoln witnessed another similar occurrence. For the rest of his journey, he considered how to construct a device to free stranded boats from shallow waters.

In this first thorough examination of Abraham Lincoln's mechanical mind, Jason Emerson brings forth the complete story of Lincoln's invention and patent as more than mere historical footnote. Emerson shows how, when, where, and why Lincoln developed his invention; how his penchant for inventions and innovation was part of his larger political belief in internal improvements and free labor principles; how his interest in the topic led him to try his hand at scholarly lecturing; and how Lincoln, as president, encouraged and even contributed to the creation of new weapons for the Union during the Civil War.

Lincoln the Inventor delves into the ramifications of Lincoln's intellectual curiosity and inventiveness, both as a civilian and as president, and considers how they allow a fresh insight into his overall character and contributed in no small way to his greatness. By understanding Lincoln the inventor, we better understand Lincoln the man.