By Katie Paul

NEW YORK, Jan 16 - Chinese social media app RedNote, known in China as Xiaohongshu, gained nearly 3 million U.S. users in one day earlier this week as a flood of self-proclaimed "TikTok Refugees" joined, according to new data from analytics firm Similarweb.

The Chinese-language app had about 3.4 million daily active users across both iOS and Android devices in the United States as of Monday, up from fewer than 700,000 the day prior, and around 300,000 the week prior, according to the Similarweb estimate. The influx of users has been driven by a looming U.S. ban on TikTok, used by 170 million Americans, on national security concerns. The data suggests an even larger shift to RedNote by U.S. users this week than was previously known, explaining its dramatic rise to the top of U.S. app store download rankings. Reuters reported on Tuesday that more than 700,000 new users had joined the app in only two days.

It also shows the platform racing ahead of TikTok sister app Lemon8, which experienced a moderate surge of its own after parent company ByteDance linked the login functions of the two apps in November.

Lemon8 had 1.7 million daily active users in the United States on Monday, up from around 1.1 million in previous weeks, according to Similarweb.

Meanwhile, U.S. usage of TikTok declined ahead of the ban, down 2.1% week over week to about 82.2 million daily active users, Similarweb said. Many Chinese users on RedNote welcomed the newcomers and responded eagerly to questions on topics such as popular Chinese dishes, city tourist sights and even China's birth policies, although there were also signs that U.S. users were testing limits established by Beijing's censors.

China for years has tightly controlled cyberspace through its "Great Firewall" censorship architecture and blocked foreign social media networks such as Instagram and X. U.S. users who have amassed followings and careers on TikTok had hoped for months that it would find a way to avoid a U.S. ban passed into law in 2023, but resignation appeared to set in this week as the Jan. 19 deadline approached.

(Reporting by Katie Paul in New York; Editing by Matthew Lewis) ((Katie.Paul@thomsonreuters.com))