The United States in 2020 experienced the biggest rise in murder since the start of national record-keeping in 1960, according to data gathered by the F.B.I. for its annual report on crime.

The Uniform Crime Report will stand as the official word on an unusually grim year, detailing a rise in murder of around 29 percent. The previous largest one-year change was a 12.7 percent increase in 1968. The national rate — murders per 100,000 — still remains about one third below the rate in the early 1990s.

The data is scheduled to be released on Monday along with a news release, but it was published early on the F.B.I.’s Crime Data Explorer website…

Separately, an independent analysis of big cities finds at least one promising sign that the murder rate may be starting to flatten this year: The increase in murders this summer does not appear to be as large as the record spike last summer.