The legendary Appalachian Trail grew by 1.9 miles in 2010.

Every December, the latest mileage and shelter information for the 11 official guides to the AT is updated from volunteers who are constantly improving the trail. Volunteer Daniel D. Chazin of Teaneck, N.J., pulls all the information together, a task he’s been performing since 1983.

This year, due to relocations  and re-measurements, increases were reported for: Massachusetts-Connecticut (0.2 mile), New York-New Jersey (0.9 mile), central Virginia (0.1 mile), and Tennessee-North Carolina (0.9 mile), while the southwest Virginia mileage was reduced by 0.1 mile.

The new official length of the AT is 2,181.0 miles.

“The Appalachian Trail Conservancy’s 2011 Data Book is an essential planning resource for any Appalachian Trail hiker; whether they are out for a day hike or hiking the entire length from Maine to Georgia,” said Brian B. King, publisher of the Appalachian Trail Conservancy.

Each year, the $6.95 Appalachian Trail Data Book is a top-selling official guide to the longest continuously marked footpath in the world. It condenses into 96 pages the high points of the series of guidebooks and maps. Information is presented at a glance in the same geographic units as the guides, with elevations for major points. Shelters, campsites, water sources, road crossings, supply sources, off-trail lodging, eateries and post offices are all easy to identify in the Data Book.

For more information about the 33rd edition of the Appalachian Trail Data Book or to purchase a copy, visit www.atctrailstore.org or call 888.287.8673.