This is the lowest per capita rate since 1968, and the second-lowest absolute number of divorces in this century.
These are rates for 2018 -- that's how far behind the reporting of these numbers typically runs.
The CDC's National Center for Health Statistics reports:
U.S. marriage rates and divorce rates, 2000-2018
Divorce rates by State: 1990, 1995, and 1999-2018
Marriage rates by State: 1990, 1995, and 1999-2018
These are per capita rates, i.e., compared to the entire population of all ages, whether married or not.
These rates have always made more sense to me if you double them, because there are two people in every divorce and every marriage. So "2.9 per 1,000" means 0.29% divorces-per-capita, but it means 0.58% of us got divorced in 2018.
This was computed without any information from California, Hawaii, Indiana, Minnesota, or New Mexico; those states did not count their divorces for 2018.
See also this chart of the per capita rates and absolute numbers of U.S. Marriages and Divorces, 1900-2012.