The reason you get or got SSSS on your boarding pass is because you were picked for a secondary security screening.
If you notice the SSSS code on your boarding pass for a flight the SSSS security code simply means you have been selected for extra security screenings, which may take additional time.
Most likely, you will need to go through a metal detector, have a pat-down and have your hands and luggage swabbed to test for explosives.
The most sensitive restricted area at the airport is the sterile area which is an area of the airport that provides access for boarding onto and off of the airplane which is also known as the Gate Area.
The access to the Gate Area is highly restricted and only ticketed passengers and people with an airport security ID card are allowed to enter the gate area via the TSA passenger screening checkpoint.
American Airports are so strict as a result of the 9/11 attacks on New York which happened on September 11th 2001.
On September 11th 2001 4 airplanes were hijacked and flown into the world trade centers in New York killing all the passengers and crew and the hijackers on board the airplanes and several people inside the world trade center buildings.
Security at airports was really ramped up and increased since the September 11th attacks to hopefully prevent any more attacks and hijacks of the planes.
"The goal of aviation security is to prevent harm to aircraft, passengers, and crew, as well as support national security and counter-terrorism policy."
Airports have to be diligent against all forms of terrorism, both foreign and domestic.
There have been incidents of American citizens hijacking aircraft.
On September 11, 2001, terrorists hijacked four commercial airplanes, using them as weapons in a coordinated attack against the United States.
You will also usually be swabbed at the airport to check for any potential explosives.
While it's generally luggage that is subject to swabbing, travelers clothes and hands may also be swabbed.
Swabbing is used as a secondary form of detecting explosives alongside full-body scanners.
While the process can be a little intimidating, a positive swab test is no need to panic.