SAT Subject US History Practice Question 534: Answer and Explanation
65. The skyscraper boom in U.S. cities was facilitated by Elisha Otis's development of
A. the revolving door
B. the elevator
C. the telephone
E. the lightbulb
Correct Answer: B
People would not walk up more than about six flights of steps; skyscrapers would never have been practical without elevators and escalators.