Security measures for commercial flights have undergone significant changes over time. Boarding a flight from a US airport now requires a boarding pass and security screening controlled by the federal government. Travelers must also be mindful of the contents of their carry-on bags.

The current security system was built in response to various attacks and attempted attacks that exposed vulnerabilities. These incidents led to the implementation of new screening procedures and regulations, such as limits on liquids in carry-on bags.

Further details are available on how these changes came about and the impact they have had on air travel. The evolution of security measures has been shaped by major events, resulting in the rigorous screening processes in place today.