Bright Side Dental, a chain with 13 offices in the metro Detroit area and elsewhere, started gathering candy donations for military care packages seven years ago. Each year, the amount that comes in has nearly doubled, totaling more than 5,000 pounds last year.

“At first, we wondered if kids would give up their candy,” said Pam Lenning, a spokeswoman for Bright Side Dental. “It’s been the complete opposite. They love it, and they’re very willing to donate. It’s turned into this fun thing in the community.”

Just days after the loot lands in trick-or-treat bags, some of those slightly used snacks will already be in the castoff pile, destined for a second life at food banks and other charitable outlets.

Operation Gratitude, which started collecting leftover candy in 2007, is one of several support-the-troops organizations that bring military-level logistics to the task of gathering, sorting and redeploying literal tons of leftover candy.

For these groups, November becomes a logistical frenzy. Last year, five staff members and more than 10,000 local volunteers wrangled 760,000 pounds of candy at Operation Gratitude. Starting the day after Halloween, it arrives in boxes of all sizes from around the country and is dumped into giant storage bins for a few weeks, until it can be divvied up for distribution.

Until recently, the organization worked out of borrowed space at a local armory, which entailed storing all of its haul outdoors. “We had running battles with some very fat squirrels,” Ms. Blashek said grimly.

The group moved indoors this year, but other enemies remain — like Pixy Stix, the strawlike paper tubes filled with powdered candy. They are the only candy that Operation Gratitude asks people not to send. The wrappers frequently break, showering sticky sugar over everything in range.