The database (three ways to access data) contains data for M2.5 and greater U.S. earthquakes and M4.5 and greater Worldwide earthquakes.
Data goes back (depending on region) a couple of thousand years.
2. ANSS (Advanced National Seismic System) Search
Includes info for earthquakes M0 and greater in the U.S.
Even more searchable databases (aka catalogs) by region available here.