Heading out to Belmont Park today? Consider using mass transit.

From Penn Station, 13 trains will go directly to the track, with stops at Woodside and Jamaica, beginning at 9:59 a.m. and running every 10-20 minutes, with the last leaving at 1:23 p.m. Eight trains will operate on the Brooklyn line, with a change at Jamaica, the first leaving Flatbush Avenue at 9:43 and the last at 1:12, with stops at Nostrand and East New York.

If you’re coming by car, get to the track early. Parking fields open at 8:15 a.m. and the gates open at 8:30. First post is 12:30 p.m., with the Belmont Stakes (post time 6:10) race 10 of a 12-race card.

Security will be tight. Coolers will be allowed in the backyard only. Anyone with coolers must use the Paddock Admissions gate or the West End entrance.

All carry-in items will be searched, and customers will be screened by metal-detecting wands. No barbecues cooking equipment is permitted.

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Celebrities expected for the Belmont Stakes include Gov. Pataki, HHR Secretary Tommy Thompson, Katie Couric, Walter Cronkite, Judge Judy, coach Bill Parcells, Martha “It’s a good thing” Stewart, Stephen Stills (but not Crosby, Nash or Young), and actors Tony Randall, Joe Pesci, Ron Silver, plus Michael Imperioli of “The Sopranos.”

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Showing speed from the start, You rebounded from her fourth-place finish in the May 3 Kentucky Oaks to win yesterday’s Grade 1, $250,000 Acorn yesterday by 7 1/4 lengths under Jerry Bailey.

Trained by Bobby Frankel, the 3-year-old filly led through blazing fractions (:44.3, :108.1) and drew clear to score easily over longshot Willa On the Move, completing the mile in 1:34 to pay $5 as the second choice. The $34.20 exacta paid. Bella Bellucci, the 3-5 favorite, came up empty in the stretch and finished a distant third.