That seemed to apply to Disneyland and other California theme parks, including Universal Studios in Los Angeles and Knott’s Berry Farm in Buena Park, Calif. But Mr. Newsom backtracked at a Thursday morning news conference, saying that his guidelines excluded large parks like Disneyland and places such as casinos and movie theaters because of “the complexity of their unique circumstances.”

Disney made its announcement regarding Disneyland’s closing shortly thereafter.

“After carefully reviewing the guidelines of the governor of California’s executive order and in the best interest of our guests and employees, we are proceeding with the closure of Disneyland Park and Disney California Adventure,” the company said in a statement. About three hours later, Disney announced the closure of Disney World, Disneyland Paris and Disney Cruise Line “in an abundance of caution and in the best interest of our guests and employees.”

Disney World, which employs 75,000 people, has experience with sudden closures. The mega-resort has been shuttered for various lengths of time because of hurricanes, including Matthew in 2016, Frances in 2004 and Floyd in 1999.

Disneyland, which employs roughly 31,000 people, has had unscheduled closures only two times since opening in 1955. The first time was in 1963 for a national day of mourning after the assassination of President Kennedy. The second was after the Sept. 11 attacks.

The California resort has grown substantially since the last closing. It now consists of two popular theme parks: Disneyland and the adjacent California Adventure, which together recorded attendance of roughly 28.7 million in 2018, the last year for which figures are available. Disney also operates three hotels in Anaheim and a shopping district called Downtown Disney, which will remain open.

Hundreds of other businesses in Anaheim and the surrounding cities rely on Disneyland to keep their cash registers ringing, from nearby mom-and-pop motels to fast-food restaurants outside the park gates to busing companies that shuttle families to and from airports. A 2018 study by professors at California State University, Fullerton, found that the Disneyland resort had an $8.5 billion annual impact on Southern California.

The coronavirus has already caused major problems for Disney overseas. The company’s entire Asian theme park operation has been closed for weeks — four parks in China and Japan that together attract 51.2 million visitors annually. Disney has said its China parks will remain shuttered until the end of March and perhaps longer, although its Shanghai property began what it called a “phased reopening” on March 9 by allowing guests to enter a shopping and dining area outside the park gates.