Those who still lack an identification that complies with the new federal law “may be diverted to a different line, have an extra step,” Kristi Noem says.

State government offices that issue driver’s licenses and state IDs have seen a significant increase in demand for REAL ID and some have extended their office hours to meet the demand. Some officials have recommended people wait for a while to get REAL ID compliant licenses and cards if they don’t have flight planned in the next few months.

Today is the first day of Real ID enforcement at airports across the U.S. Here's what travelers have to know before taking to the skies.