The best-known antiques fair in the country, the Brimfield Antique Show (www.brimfieldshow.com [1]), occurs yearly in Brimfield, the town next door to Sturbridge [2]. Every September, the small town of 3,000 people explodes in population, as 30,000 visitors and 5,000 dealers descend upon it to barter over their wares.
Links:
[1] http://www.brimfieldshow.com
[2] http://www.moon.com/destinations/new-england/massachusetts/eastern-massachusetts/worcester-and-vicinity/sturbridge