text: "Lombard Street is best known for one block on Russian Hill between Hyde and Leavenworth Streets, in which the roadway has eight sharp turns (or switchbacks) that have earned the street the distinction of being "the crookedest [most winding] street in the United States."\n\nThe switchback design, first suggested by property owner Carl Henry and instituted in 1922, was born out of necessity in order to reduce the hill's natural 27° slope which was too steep for most vehicles to climb and a serious hazard to pedestrians used to a more reasonable sixteen-degree incline. The speed limit is a mere 5 mph (10 km/h) on the crooked section, which is about 1/4 mile (400 m) long.