Regionally, the term refers to the coastal states and area east of the Appalachian Mountains that have shoreline on the Atlantic Ocean, from north to south, Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut, New York, New Jersey, Delaware, Maryland, Virginia, North Carolina, South Carolina, Georgia, and …

What exactly is the Eastern Seaboard?

Eastern Seaboard, also called Atlantic Seaboard, region of the eastern United States, fronting the Atlantic Ocean and extending from Maine in the north to Florida in the south.

What cities are in the Eastern Seaboard?

East Coast Cities 2021
New York City (8.6 million)Philadelphia (1.6 million)Charlotte (859,000)Jacksonville (821,784)Washington D.C. (703,000)

I think back to Physical Geomorphology — the Eastern Seaboard in the US is a shoreline of emergence and the Western is not a “seaboard” — because the west coast is a shoreline of nothing (it is totally different geologically).