Which lock is most commonly used in the United States for exterior building doors?

The pin-tumbler lock is the most commonly used type of lock for exterior building doors in the United States due to its widespread acceptance, simplicity, and efficiency. This lock operates using a set of pins that are aligned at different heights by the correct key. When the key is inserted, the pins are pushed up and down, allowing the lock cylinder to turn and engage the locking mechanism.

This design balances security with ease of use, making it a popular choice for residential and commercial properties alike. Furthermore, pin-tumbler locks can be easily rekeyed, which provides additional convenience for property owners who may need to change the locks without replacing the entire locking system. The reliability and adaptability of pin-tumbler locks contribute significantly to their predominance in securing exterior doors across a variety of building types in the U.S.