Most airports around the United States operated smoothly as new REAL ID requirements took effect because travelers without the updated document were still allowed to move through security easily. Those without the IDs were given flyers informing them that going forward they would need to present "REAL ID or other acceptable form of identification for your next flight or you may expect delays." REAL ID requirements for those flying within the U.S. began Wednesday after more than 20 years of delays. Many airports reported security checkpoint wait times of a few minutes on their websites.

The head of Homeland Security says travelers who aren't REAL ID compliant by the upcoming deadline this week will still be able to fly but should be prepared for extra scrutiny. Kristi Noem told a congressional panel that 81% of travelers already have IDs that comply with the REAL ID requirements. She says security checkpoints will also be accepting passports and tribal identification when the deadline hits Wednesday. She says those who still lack an identification that complies with the REAL ID law "may be diverted to a different line, have an extra step." But they will still be allowed to fly.

The deadline to get a REAL ID is fast approaching after years of postponements and delays. Starting May 7, your license or identification card will need to be REAL ID-compliant to fly domestically in the U.S. Unfortunately, it doesn't seem like there will be another delay in the deadline this time. Here are some of the key things to know about REAL ID, including how to get one, why you even need one in the first place, and what happens if you don't have one by May 7.

As drivers on U.S. highways cross from one state to another, they often are greeted by a large "Welcome to ..." sign.