Nassau County and state officials Friday urged residents attending Saturday’s 148th running of the Belmont Stakes to be prepared for road closures and heightened security.

While attendance is expected to dip this year without a Triple Crown on the line, tens of thousands of spectators are expected to travel by car and the Long Island Rail Road to Belmont Park.

“The eyes of the world will be on Nassau County and the Belmont Stakes,” Nassau County Executive Edward Mangano said at a news conference Friday in Garden City.

Plainfield Avenue will be closed between Hempstead Turnpike and Vandewater Avenue from 8 a.m. to 9 p.m. Lengthy delays are also expected on the Cross Island Parkway and on Hempstead Turnpike throughout the day.

The Nassau County Police Department is coordinating its security measures with the MTA, State Police and the state Division of Homeland Security and Emergency Services, acting Police Commissioner Thomas Krumpter said.

No backpacks, coolers, luggage or duffel bags will be allowed into Belmont Park. Food must be brought in see-through plastic containers or bags.

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The LIRR is expecting 20,000 additional riders to and from Belmont, compared with 50,000 last year.

The LIRR, which spent $5 million last year to upgrade the Belmont station, has scheduled 20 trains to Belmont on Saturday, with 18 trains originating at Penn Station and two others at Jamaica. The first train departs Penn Station at 9:39 a.m. and the last will leave at 4:32 p.m.

The first train will depart Belmont at 4:51 p.m. After the Stakes, the railroad will operate on a “load and go” schedule, with trains leaving as soon as they fill up, said LIRR executive vice president Elisa Picca.

The first race Saturday is set for 11:35 a.m. with the Stakes scheduled to begin at 6:36 p.m.

The Belmont racing season, from April 29 to July 17, generates roughly $10 million for Nassau’s economy, Mangano said. Officials could not specify how much would be generated this weekend alone.

Officials also have announced that entertainers scheduled to perform Saturday at Belmont Park include the rock band Daughtry and the cast of the Broadway show “Beautiful: The Carole King Musical.”