There is a popular myth that Henry Ford invented the automobile assembly line. It was actually a fellow named Ransome Olds who was the first person to mass produce cars in the U.S.
Olds began making steam and gasoline engines with his father, Pliny Fisk Olds, in Lansing, Michigan, in 1885. Olds designed his first steam powered car in 1887, and 12 years later, armed with growing knowledge of gas powered engines, started the Olds Motor Works in Detroit.
Unfortunately, before production began, his factory burned down. Exactly one prototype – a single cylinder buggy – survived. But he set up another factory and soon the Oldsmobile Gas Buggy – that’s what it was called – was selling very well.
The name Oldsmobile was first used in 1900, though the cars were known simply as Olds. It was the nation’s leading manufacturer of cars from 1901 to 1904, when Ransome Olds left the company to start another car company making something called “Reo” cars, or R-E-O, derived from his initials. The Reos were similar to Oldsmobiles but for some reason never sold very well.
Despite the departure of Olds, or perhaps because of it, the Oldsmobile Company prospered, and in 1908 was purchased by William C. Durant. Along with Buick, it became the foundation of General Motors.
UPDATE (10:50 p.m.): Corrected the reference to William Durant. Will Durant was the historian.

