Conversation so far:
When did Rogers Morton start his career in congress?
Rogers Morton was re-elected to Congress four more times, and served from 1963 until 1971.
What state was Rogers Morton elected to congress from?
Rogers Morton served as a member of the U.S. House of Representatives from Maryland.
What state is the Assateague Island national park located?
Assateague State Park is a public recreation area in Worcester County, Maryland.

Question: How long has he been in congress?
Self-contained rewrite: How long has Rogers Morton been in congress?