Originally Posted by Hektore

The Appalacian Trail (AT) is 2175 miles (~3500km) from end to end. You can spend as much time as you would like on it. I'm not aware of any sections that are closed for the winter, but it can get pretty nasty this time of year in the northern latitudes, If I recall correctly most through hikers looking to complete the trail start at the trail head in Georgia in late march/early April and hike north with the warming weather.