13 Colonies is an annual Special Event held during the 4th Of July Week (1-7th July 2017). Participants try to make contact(s) with all 13 Colony Stations, and the 2 Bonus Stations. You do not need to make contact will all 13 to be awarded the 2017 13 Colonies certificate.
Making contact with all 13 stations is known as a "Clean Sweep", and whilst working the 2 bonus stations provides kudos, you do not need the 2 bonus stations for a clean sweep.
13 Colonies Bonus Stations
WM3PEN - Philadelphia, PA, where independence was declared. The 13 Colonies certificate will have a Liberty Bell added for a contact with "WM3PEN"
GB13COL - Durham, England. Making a Contact with "GB13COL", the 13 Colonies certificate will have an endorsement of the "British Standard".
More information - http://www.13colonies.net/