View photos from the opening day of Disneyland on 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. The following day, it opened to the public, featuring twenty attractions. The Special Sunday events, including the dedication, were televised nationwide and anchored by three of Walt Disney’s friends from Hollywood: Art Linkletter, Bob Cummings, and Ronald Reagan. ABC broadcast the event live, during which many guests tripped over the television camera cables.

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 101 °F (38 °C), 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.