Hikers also have to determine their resupply points. Resupply points are towns or post offices where hikers replenish food and other supplies such as cooking fuel. Hikers can ship packages to themselves at the U.S. Post Offices along the trail, resupply at general and grocery stores along the trail, or any combination of the two. The final major logistical step is to create an approximate schedule for completion. Thru hikers have to make sure they complete enough miles every day to reach the opposite end of the trail before weather conditions make sections impassable. For northbound thru-hikers, deep snow pack in the Sierra Nevada can prevent an early start. The timing is a balance between not getting to the Sierra too soon nor the Northern Cascades too late. Most hikers cover about 20 miles (32 km) per day.
