Littorally

Anyone know the origin for the term "Eastern Seaboard"?

I don't know the history. Other than it's eastern and it's a seaboard.

Dictionary.com:
seaboard
\Sea"board`\, n. [Sea + board, F. bord side.] The seashore; seacoast. --Ld. Berners.

Merriam-Webster:
Main Entry: sea.board
Pronunciation: 'sE-"bOrd, -"bord
Function: noun

SEACOAST; also : the country bordering a seacoast

- seaboard adjective

By convention, the USA has a West Coast but an Eastern Seaboard. It's difficult to find a reason. The early colonists landed on the Eastern Seaboard; perhaps the name dates back to their vocabulary.