Large U.S. law firms have been expanding their geographic footprints wildly in the last 17 years, a new report shows, with major implications for regional and local law firms.

The 250 largest law firms by head count (NLJ 250) added more than 1,000 U.S. offices between 2001 and 2017, a recently released study by ALM Intelligence found, making certain legal markets in the country much more crowded.