Lake Compounce is the oldest continuously operating amusement park in the United States. It is located in Bristol and Southington. It includes not only the amusement park, but a beach and waterpark too.
Encyclopedias:
Academic Kids (Challenge)
Websites:
ConnecticutHistory.org
Books:
It's My State!: Connecticut by Michael Burgan (page 14) (available through Destiny Discover)