Modified service was restored between Washington, D.C. and New York City after 11 a.m.
Service from New York to Boston is expected to resume this morning.
Amtrak's Keystone service that runs to and from New York, Philadelphia and Harrisburg is also operating on a modified plan.
Amtrak said passengers with travel plans may adjust their plans or review refund information through Amtrak.com, smartphone apps or by calling 800-USA-Rail.