Airport security lines are almost a given when traveling.

The Sept. 11 attacks led to the creation of government agencies like the Department of Homeland Security and the Transportation Security Administration, or TSA, and federal regulations tightened up security in the aftermath.

Since then, how people get through security has continued to evolve. While they have figured out how to use state-of-the-art scanners and other technology, one very visible problem has stuck around.

“Here we are, 22 some odd years later, where we’re still trying to figure out how to keep the line short,” said Jeff Price, a professor of aviation at Metropolitan State University of Denver. “We’re still trying to figure out how to keep them moving. A lot of people don’t understand that moving the lines quickly is not just an efficiency function and a passenger experience element; it’s also a security element because the more passengers I have packed into a public area waiting to go through the screening process, the more vulnerable I am to things like suicide bombers, active shooters.”

Price knows this firsthand from his past experience as an assistant security director at Denver International Airport and as a manager of a smaller regional airport. He told Scripps News there are a few distinctions within security.

Most airports rely on the TSA to administer the process. A handful, including San Francisco and Kansas City, rely on private contractors, but they all adhere to tight TSA guidelines, making them all look the same in operation.

But the lines can look very different depending on the airport and how much a person is willing to pay.

Airport security lines now have multiple, tiered options for getting through. 

There’s the regular line where all the rules apply, there are no extra costs and security just needs