Disneyland turns 50 this year and a new parade, fireworks show and attractions will be part of its long party that begins May 5.

To get the most bucks for the bang, the celebration — called “The Happiest Homecoming on Earth” — will continue for 18 months at Disneyland and its sister parks, from Orlando to Paris and Tokyo — and at the new Disneyland in Hong Kong (which opens in September).

Arising among what were orange groves and walnut farms in Anaheim, near Los Angeles, Disneyland was the brainchild of Walt Disney and the first of what is now a theme-park empire on three continents.

Disneyland opened July 17, 1955, to an invited audience. But eager gate-crashers and those with counterfeit tickets swelled the 6,000 invited guests to 28,000.

On opening day, there were hourslong traffic jams around Disneyland. Inside, overloaded rides broke down; restaurants ran out of food and drinks; and women’s high heels stuck in the freshly-poured asphalt of Main Street USA.

Since then, Disney theme parks have become experts in managing crowds — and more than 500 million visitors have come to Disneyland alone. It opened with 18 major attractions; it now has more than 60 adventures/attractions spread over 85 acres, with many more in the adjoining California Adventure theme park.

If you want to join the party on May 5 — a date chosen because its 5/5/05 designation fits nicely with a 50th celebration — be ready for big crowds then and the following weekend. And be ready for really big crowds on July 17, the actual 50th anniversary.

Here’s some of what’s planned for Disneyland’s 50th throughout the 18-month period:

l A new nightly fireworks show, called “Remember … Dreams Come True” begins May 5, with new pyrotechnics, music and special lighting effects. Disneyland calls it “the most elaborate fireworks display in the history of the park.”

l A new parade, “Walt Disney’s Parade of Dreams,” also begins May 5 with rolling stages, acrobats, Disney characters, music and more. Scenes from favorite Disney movies will be re-enacted in the daily parade (twice a day at peak times) on Main Street.

l Sleeping Beauty Castle’s “new look” will be unveiled May 5. The Disneyland icon will be festooned with banners, trimmed with gold paint and illuminated nightly with a kaleidoscope of colors and images.

l Space Mountain reopens July 15 after a major renovation. The indoor roller coaster will have new special effects and a new, on-board soundtrack.

l The exhibit “Disneyland: The First 50 Years” opens May 5 in the Main Street Opera House, with vintage films, artwork and more celebrating the theme park’s development.

l In Disney’s California Adventure theme park, which adjoins Disneyland, “Block Party Bash” begins May 5. Street parties featuring Disney characters will be staged throughout the park.

l “Buzz Lightyear Astro Blasters” opened earlier this month. Inspired by the popular “Toy Story 2” film, ridegoers command a space mission, fighting invaders with laser cannons.