Founded in Milwaukee in 1903, Harley-Davidson grew from William S. Harley’s bicycle-engine idea and work with Arthur and Walter Davidson into a major motorcycle manufacturer. After early underpowered machines, the company developed stronger designs, expanded from a backyard shed to a Juneau Avenue factory, and rapidly increased production. It became known especially for heavyweight cruiser motorcycles, V-twin engines, and an influential customization culture, while also supplying police and military markets. Harley-Davidson survived the Great Depression, served heavily in both world wars, and by 1920 had become the world’s largest motorcycle manufacturer. It remains a leading Milwaukee industrial name and a lasting symbol of American motorcycling.