The 5th congressional district is in eastern Massachusetts. On July 15th, 2013, Ed Markey resigned from the seat to become the junior Senator from Massachusetts, prompting a special election to fill the vacancy. A primary is planned for October 15, 2013, and the general election is planned for December 10, 2013.
The district has been in Democratic hands without interruption since 1974. Before Paul Tsongas' victory that year, it had only elected three Democrats in its entire existence and had been in Republican hands since 1895.
All this text has been borrowed with love from the wikipedia article about the MA-05.