PETERSON AIR FORCE BASE, Colo. (AP) — Volunteers have pulled on their Santa hats, and are answering phone lines and monitoring wall-size tracking screens as NORAD Tracks Santa begins its 57th annual goodwill mission.

The first shift of Santa trackers started taking calls early Monday at 877-HI-NORAD (877-446-6723), telling children — and some adults — when Santa is due at their house. The last shift won’t end until nearly 24 hours later.