From Wikipedia's History of Delaware page:
"The history of Delaware as a political entity dates back to the early colonization of North American by European settlers. It is made up of three counties established since 1680, before the time ofWilliam Penn. Each had its own settlement history. Their early inhabitants tended to identify more closely with the county than the colony or state. Large parts of southern and western Delaware were thought to have been in Maryland until 1767. All of the state has existed in the wide economic and political circle of Philadelphia."
Read the rest at Wikipedia.
A blog post from one of Farzad Rostami, Delaware blogs.