Children run through the gate of Sleeping Beauty's Castle at Disneyland, Walt Disney's theme park, in July 1955. The park opened to the public the week of July 17, 1955.

Children run through the gate of Sleeping Beauty’s Castle at Disneyland, Walt Disney’s theme park, in July 1955. The park opened to the public the week of July 17, 1955.

Disneyland was dedicated at an “International Press Preview” event held on Sunday, July 17, 1955, which was open only to invited guests and the media. Although 28,000 people attended the event, only about half of those were invitees, the rest having purchased counterfeit tickets, or even sneaked into the park by climbing over the fence. A reporter noticed all the construction still ongoing and asked Walt Disney if Disneyland would ever be finished. Disney replied in what has become an oft quoted quote: “Disneyland will never be completed, as long as there is imagination left in the world.”

Traffic was delayed on the two-lane Harbor Boulevard. Famous figures who were scheduled to show up every two hours showed up all at once. The temperature was an unusually high 38 °C (101 °F), and because of a local plumbers’ strike, Disney was given a choice of having working drinking fountains or running toilets. He chose the latter, leaving many drinking fountains dry.

This generated negative publicity since Pepsi sponsored the park’s opening; disappointed guests believed the inoperable fountains were a cynical way to sell soda, while other vendors ran out of food. The asphalt that had been poured that morning was soft enough to let women’s high-heeled shoes sink into it. Some parents threw their children over the crowd’s shoulders to get them onto rides, such as the King Arthur Carrousel. In later years, Disney and his 1955 executives referred to July 17, 1955, as “Black Sunday”. After the extremely negative press from the preview opening, Walt Disney invited attendees back for a private “second day” to experience Disneyland properly.

At the time, and during the lifetimes of Walt and Roy Disney, July 17 was considered merely a preview, with July 18 the official opening day. Since then, aided by memories of the television broadcast, the company has adopted July 17 as the official date, the one commemorated every year as Disneyland’s birthday.

Mickey and Minnie Mouse appear at Disneyland's opening day, on July 17, 1955.

Mickey and Minnie Mouse appear at Disneyland’s opening day, on July 17, 1955.

The movie producer and animator Walt Disney smiles as he stands in front of Sleeping Beauty's Castle at the grand opening of Disneyland in 1955.

The movie producer and animator Walt Disney smiles as he stands in front of Sleeping Beauty’s Castle at the grand opening of Disneyland in 1955.

The Disneyland parking lot, full on opening day, July 17, 1955.

The Disneyland parking lot, full on opening day, July 17, 1955.

An aerial view shows Disneyland as guests attend opening-day festivities in Anaheim, California, on July 17, 1955.

An aerial view shows Disneyland as guests attend opening-day festivities in Anaheim, California, on July 17, 1955.

Dumbo and other characters from Disney movies appear in a parade down Main Street, U.S.A., at the Disneyland opening on July 17, 1955.

Dumbo and other characters from Disney movies appear in a parade down Main Street, U.S.A., at the Disneyland opening on July 17, 1955.

Disneyland's opening-day parade, photographed on July 17, 1955.

Disneyland’s opening-day parade, photographed on July 17, 1955.

Original caption:

Original caption: “Eddie Fisher (left) was a host at the opening of Walt Disney’s ‘Disneyland,’ where he served on the Coca-Cola refreshment corner. Shown are Eddie Fisher as he gives a drink to aluminum-clad spaceman Don MacDonald, as Debbie Reynolds looks on.”

Visitors take a ride on Mr. Toad's Wild Ride at Disneyland on July 17, 1955.

Visitors take a ride on Mr. Toad’s Wild Ride at Disneyland on July 17, 1955.

A crowded Mark Twain Riverboat sails at Disneyland in July 1955.

A crowded Mark Twain Riverboat sails at Disneyland in July 1955.

Showgirls in costume sit at an outdoor table and drink from mugs at Disneyland in July 1955.

Showgirls in costume sit at an outdoor table and drink from mugs at Disneyland in July 1955.

A children's saloon, the Golden Horseshoe, photographed at Disneyland on July 17, 1955.

A children’s saloon, the Golden Horseshoe, photographed at Disneyland on July 17, 1955.

A pack of

A pack of “wild animals,” caged for safekeeping at Disneyland in July 1955.

Guests enjoy the Autopia attraction on July 17, 1955.

Guests enjoy the Autopia attraction on July 17, 1955.

People rest in Tomorrowland's Space Port on July 17, 1955.

People rest in Tomorrowland’s Space Port on July 17, 1955.

Tourists enter Frontierland, a re-creation of the Old West, in Disneyland, ca. 1955.

Tourists enter Frontierland, a re-creation of the Old West, in Disneyland, ca. 1955.

The Painted Desert in Frontierland, photographed on July 17, 1955.

The Painted Desert in Frontierland, photographed on July 17, 1955.

Mickey Mouse rides in the locomotive cab of a train (with Walt Disney just to his left) as it arrives at a station in Disneyland on July 18, 1955.

Mickey Mouse rides in the locomotive cab of a train (with Walt Disney just to his left) as it arrives at a station in Disneyland on July 18, 1955.

Crowds of people watch the Tomorrowland portion of a parade celebrating the opening of the Disneyland amusement park on July 17, 1955.

Crowds of people watch the Tomorrowland portion of a parade celebrating the opening of the Disneyland amusement park on July 17, 1955.

Parade participants and costumed Disney characters ready themselves for the televised grand opening of Disneyland on July 17, 1955.

Parade participants and costumed Disney characters ready themselves for the televised grand opening of Disneyland on July 17, 1955.

Children run into Disneyland on opening day, July 17, 1955.

Children run into Disneyland on opening day, July 17, 1955.

Visitors ride the Mad Hatter's Tea Party attraction in Fantasyland on July 17, 1955.

Visitors ride the Mad Hatter’s Tea Party attraction in Fantasyland on July 17, 1955.

Park attendees relax under sunshades near a TWA rocket in Disneyland in July 1955.

Park attendees relax under sunshades near a TWA rocket in Disneyland in July 1955.

A view of the Tomorrowland Boats (renamed the Phantom Boats) attraction at Disneyland in July 1955. The attraction lasted only from the park's opening until 1956.

A view of the Tomorrowland Boats (renamed the Phantom Boats) attraction at Disneyland in July 1955. The attraction lasted only from the park’s opening until 1956.

A little girl laughs with excitement while riding a carousel at Disneyland in July 1955.

A little girl laughs with excitement while riding a carousel at Disneyland in July 1955.

(Photo credit: The LIFE Picture Collection / USC Libraries / Corbis via Getty).