Montana Governor Signs Total Ban of TikTok in the State

The governor of Montana, Greg Gianforte, signed a bill on Wednesday to ban TikTok from operating inside the state, the most extreme prohibition of the app in the nation and one that will almost certainly be challenged in court. The ban will take effect on Jan. 1.

“Today, Montana takes the most decisive action of any state to protect Montanans’ private data and sensitive personal information from being harvested by the Chinese Communist Party,” Mr. Gianforte, a Republican, said in a news release.

The Montana Legislature introduced the bill in February, leading to months of debate. The proposal, which would affect everyday users of the popular short-form video app, significantly escalated a national rush to ban TikTok on government devices based on concerns about the company’s ownership by the Chinese company ByteDance. The battle over the bill offered a glimpse of what the United States might encounter nationally if lawmakers or the White House attempt a nationwide ban of TikTok, which has been floated in recent months.

TikTok, which says it has 7,000 employees in the United States, has been fighting back in the state for months. It has run ads featuring Montana small businesses that use TikTok and given prewritten emails to users so they could contact Mr. Gianforte about opposing the bill.

The legislation prohibits mobile app stores, like those run by Apple and Google, from offering TikTok within the state. A trade group funded by Apple and Google has said in recent months that it is impossible for the companies to prevent access to TikTok in a single state.