In 2014, the average live weight of the typical turkey that will be consumed during the Thanksgiving holiday is 30.2 pounds.
Compared to the 1970's, when the live weight of turkeys produced in the United States had stagnated at 18.6 pounds per bird, that makes 2014's turkey about 61% heavier. Or about 88% heavier than the typical "heritage" turkey that might be found in the wild!
References
The Poultry Site. USDA Livestock, Dairy and Poultry Outlook - November 2014. [PDF Document]. 17 November 2014.
U.S. Department of Agriculture. Turkeys Raised. [PDF Document]. 30 September 2014.
National Turkey Federation. Sourcebook. [PDF Document]. October 2013.