Those headed back to Southern California from Las Vegas after Memorial Day weekend can expect heavy traffic on Interstate 15.

Heavy traffic moves along South Las Vegas Boulevard approaching the Gold Strike Hotel & Gambling Hall in Jean on Monday, May 28, 2018. (Richard Brian/Las Vegas Review-Journal) @vegasphotograph

Heavy traffic moves along southbound Interstate 15 near Jean on Monday, May 28, 2018. (Richard Brian/Las Vegas Review-Journal) @vegasphotograph

Traffic is heavy on southbound Interstate 15 as visitors leave Las Vegas, Monday, May 28, 2018. (RTC Fast Cameras)

Those headed back to Southern California from Las Vegas after Memorial Day weekend can expect heavy traffic on Interstate 15.

The backup on southbound I-15 began piling up about 8:55 a.m., when the Regional Transportation Commission of Southern Nevada reported a 9-mile backup near the stateline. By 10 a.m., the commission said the backup spanned 12 miles on I-15.

Drivers should expect long delays, the commission said.

Contact Rio Lacanlale at rlacanlale@reviewjournal.com or 702-383-0381. Follow @riolacanlale on Twitter.