The holidays can be a tough time for some families.

The U.S. Postal Service has been helping people over the holidays for more than 100 years with its Operation Santa.

Spokeswoman Elizabeth Najduch says an adult or child can write a letter to Santa and someone can adopt their letter to fulfill their wishes. Najduck says if you write a letter to Santa, include a complete return address , postage and mail it. It has to be postmarked by December 10th.

Those who want to adopt a aletter have to register at USPS.com.