Airlines began enacting stricter security screenings and measures after 9/11. Liquids, sharp objects and other various items have become severely restricted. For example, Transportation Security Administration (TSA) regulations prevent passengers from carrying on any more than a 1-quart plastic zip-top bag of 3-oz. clear bottles of liquid.
The TSA was created directly in response to the events of 9/11. A division of the Department of Homeland Security, the TSA is responsible for airport security across the nation. When you fly, the TSA inspects you and your bags at security.
The demand for commercial air travel decreased after 9/11. Directly following the attacks, demand for air travel (people flying) went down by more than 30 percent, which eventually shrunk to a 7.4 percent decrease in demand that lasted well into 2003, according to Brown University.
While the airline industry was already in dire financial straights before 9/11, the attacks hurt the industry even more. Immediately following the attacks, the entire airline industry was completely shutdown for four days, costing the industry roughly $1.4 billion in revenue, with over $7 billion lost in all of 2001.
