If you are traveling after May 7 and you don’t have a Real ID, what will happen when you reach security? Well, you’ll likely still be able to fly — at least as the Transportation Security Administration begins enforcement — but added measures could result in a lengthy process that may leave many at risk of missing their flights.

“Homeland Security has let us know that even after May 7th, there will be essentially a two-year enforcement period where they’re not going to not let people onto an airplane,” Illinois Secretary of State Alexi Giannoulias said this week as the deadline approached.

That said, Adam Stahl, acting deputy TSA administrator, told NBC Chicago to expect a potentially cumbersome experience after Wednesday if you don’t have Real ID-compliant identification.

“We encourage you, if you do not have a proper Real ID-compliant form of identification, to please bring an alternative like a passport, like a military ID card or a global entry card,” Stahl said. “If you do not have those and you come with a non-Real ID compliant form of state identification, you’ll be okay, you’ll get through, but you may be susceptible to some additional screening measures.”

Kristi Noem told a Congressional panel 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 people will be allowed to fly,” she said. “We will make sure it’s as seamless as possible.”

So what counts as Real ID-compliant?

Beyond a Real ID license, which can be identified based on a symbol (in Illinois, a star) in the top corner of the card, U.S. Passports, Global Entry cards, or passport cards are considered viable options, among other things.

“We really ask you to please plan ahead,” Stahl said for those who try to travel without proper identification after the deadline.

Depending on which airport you are traveling through, the time of day, and the amount of other travelers, delays could be extensive.

For those who do have a Real ID or bring “a sufficient alternative,” however, Stahl said “we are confident that you will not have impacts at checkpoint.”

Unprecedented lines have been seen at Chicago-area DMVs and the downtown Chicago Real ID supercenter in the days leading up to the deadline Wednesday.

“The line is like nothing we have ever seen in the state of Illinois,” Giannoulias said.

But officials stressed that those securing their Real ID now will not be able to use the paper they receive first to travel.

“You walk out with a piece of paper, that does not qualify as a Real ID,” Giannoulias said.

While security officials are encouraging travelers to secure a Real ID as soon as possible, Giannoulias stressed that rushing before the deadline may not be necessary.

“The Real ID deadline is not really a deadline,” he said, adding that his office will continue providing Real IDs for those who need them after May 7. “The message to those folks who are flocking to facilities today thinking that they will not get a Real ID in 48 hours from now, that is not accurate.”

So who needs a Real ID and when? What happens if you don’t have one and you need it to travel?

Here’s what to know:

What is a Real ID?

It’s a driver’s license or other state-issued ID that meets security requirements mandated in a 2005 law passed in the aftermath of the Sept. 11, 2001, terrorist attacks.

Obtaining an ID with the designation — indicated by a white star in a yellow circle in most states — means taking more documents to the motor vehicle agency than most states require for regular IDs.

Who needs a Real ID?

According to Giannoulias, “most Illinoisans do not need one before May 7.”

Contrary to misinformation, a Real ID won’t be needed to drive.

“We want Illinoisans to make sure that they truly need a Real ID before coming to a facility” Giannoulias said, touting the state’s new Real ID portal. “For instance, it will ask you if you have a U.S. passport, global entry card, or military ID. If you respond yes for any of them, it informs you that you do not need a Real ID. And even if you don’t have one of those and you are not flying on a commercial airline on May 7 or in early summer, you also do not need a Real ID. If you’ve gone through the portal and determined that you need a Real ID, it will present you with DMV walk-in options and let you know how you can schedule an appointment at a facility near you.”

The Illinois Secretary of State’s office calls Real IDs are “optional” for many on its online portal. More information can be found here.

How do you know if your license is a Real ID?

REAL ID-compliant cards will have a specific marking on the top portion of the card. In Illinois, that marking is a star.

What else can you bring to the airport if you don’t have a Real ID?

Those without a Real ID, or Real ID compliant form of identification, should anticipate longer wait times in airport security, the TSA warned last week in Chicago. Travelers without one can expect to see delays, additional screening, and the possibility of not getting through TSA security should their documents not fulfill the requirements, the agency said.

But you may already have an acceptable and compliant form of identification at home. Those include U.S. Passports, Passport cards, or Global Entry.

According TSA, here’s the full list of Real ID compliant forms of identification you can use at the airport, though TSA warned the list of acceptable documents could change without notice:

• State-issued Enhanced Driver’s License (EDL) or Enhanced ID (EID)
• U.S. passport
• U.S. passport card
• DHS trusted traveler cards (Global Entry, NEXUS, SENTRI, FAST)
• U.S. Department of Defense ID, including IDs issued to dependents
• Permanent resident card
• Border crossing card
• An acceptable photo ID issued by a federally recognized Tribal Nation/Indian Tribe, including Enhanced Tribal Cards (ETCs).
• HSPD-12 PIV card
• Foreign government-issued passport
• Canadian provincial driver’s license or Indian and Northern Affairs Canada card
• Transportation worker identification credential
• U.S. Citizenship and Immigration Services Employment Authorization Card (I-766)
• U.S. Merchant Mariner Credential
• Veteran Health Identification Card (VHIC)

Where can you get a Real ID?

The Illinois Secretary of State’s Office has a section of their website that allows residents to make appointments to get their Real ID-compliant licenses and cards. But beware, officials say, Real ID appointments may be hard to get.

“Due to the federally-mandated Real ID requirements, our facilities and website have been overwhelmed with requests for Real IDs,” a message on the Illinois Secretary of States website said. “As a result, we’re asking everyone to make sure they really need a REAL ID before booking an appointment or visiting a facility. The May 7th date is NOT a final deadline and everyone can travel with a valid U.S. Passport. Thank you.”

As part of the ongoing efforts to work through the increased demand, the office added nearly 2,500 additional daily appointments at the 44 appointment-only DMVs in Chicago and its suburbs, according to a press release.

A large former Walgreens building in Chicago’s Loop is often used as a “voting supersite” during election season. But these days, 191 N. Clark St. is dubbed the “Real ID Supercenter.”

Giannoulious announced the new downtown supercenter, equipped with 30 individual service counters, earlier this month. The center, which accommodates walk-ins only, is open from 7:30 a.m. to 5 p.m. Monday through Friday. Photos and video from the supercenter have showed long lines, winding around for blocks.

The supercenter is expected to stay open well beyond the May 7 Real ID deadline, per Giannoulias.

The Real ID supercenter comes the Illinois Secretary of State’s office announced a slew of initiatives around getting a Real ID in Illinois, including additional hours at DMVs, as well as an online portal to help determine which residents may need one.

What do you need to bring to get a Real ID? Here’s a checklist

Below, you’ll find a checklist of all the necessary documents you will need to submit at a DMV facility.

How much does a Real ID cost?

According to the Secretary of State’s Office, the cards will cost $30, the same cost for a regular Illinois driver’s license or identification card.

Associated Press contributed to this report.