How much candy?

24.7 pounds = per capita consumption of candy in the U.S. in 2010.
According to Google, 1 pound = 453.59 grams.
According to my personal candy stash, a 58.7 gram Snickers bar* has 280 calories.

With some fancy math, we can figure out that it takes about 7.73 Snickers bars to make a pound, which adds up to 2,165 calories per pound of candy (give or take a calorie).

Multiply that by 24.7 pounds...
and you get more than 53,400 calories worth of candy consumed per year, per capita, in the U.S.

Divide that by an approximate 105 calories per mile run

...and you would need to run more than 509 miles (19 marathons!) to burn off the average American's annual candy consumption!

*Note: I used what I had available. Different candies might yield somewhat higher or lower results.

Data sources:
U.S. Census Bureau, Current Industrial Reports, Confectionery: 2010
Google Calculator
Runner's World "How Many Calories Are You Really Burning?"
Author's calculations