The northern boundary of the GREAT SMOKY MOUNTAINS NATIONAL PARK , which stretches for seventy miles along the Tennessee-North Carolina border, is just two miles south of Gatlinburg on US-441.

Don't expect immediate tranquility, however: the roads, particularly in the fall, can be lined almost bumper-to-bumper with cars, and if you're not staying in Gatlinburg it's best to use the well-marked bypass rather than drive through the town.

The Smokies , within a day's drive of the major urban centers of the east coast and the Great Lakes - and of two-thirds of the entire US population - attract over nine million visitors per year, more than twice as many as any other national park. These heavily contorted peaks are named for the bluish haze that hangs over them, made up of moisture and hydrocarbons released by the lush vegetation (a mature tree emits up to 900 gallons on a summer day).

Since the Sixties, however, air pollution has been adding sulphates to the filmy smoke, and has cut back visibility by thirty percent. More than 120 tree species and over 1400 flowering plants clothe the mountains and meadows in color from early spring to late fall. Sixteen peaks rise above 6000ft, their steep elevation accounting for dramatic changes in climate.

The most popular times to visit are between late March and mid-May, for the delicate spring flowers, and during the second half of October, when the hills are shrouded in a magnificent canopy of glaring reds, subtle yellows and faded browns. During June and July, rhododendrons blaze fiercely in the sometimes stifling summer heat. Just inside the park on US-441, the main artery running through to North Carolina, Sugarlands Visitor Center (summer daily 8am-7pm; fall and spring daily 8am-6pm; winter daily 8am-5pm) is a useful source of leaflets covering hiking trails, driving tours, forests and wildlife. From here a ten-mile drive rises to Newfound Gap on the state line, where a seven-mile spur road winds its way up to Clingman's Dome , at 6643ft the highest point in the park and in all Tennessee.

A surreal concrete spiral walkway on top affords a panoramic, though hazy, view of the mountains, rather spoiled by the fact that virtually all the mature balsam firs in the area have been killed off by insect infestation.

The scenic Little River Road branches off back at Sugarlands toward Cades Cove , where another visitor center (mid-April to Oct 9am-7pm; tel 865/436-1230 for winter hours) is situated halfway round an eleven-mile driving loop, always jam-packed with cars in summer and fall. Along the route, deserted barns, homesteads, mills and churches stand as a reminder of the farmers who carved out a living from this wilderness, before having to move out when national park status was conferred in 1934.

Quieter Hwy-321 , on the other side of Sugarlands, branches off onto a gravel road toward the beautiful Greenbrier area. If you really want to get away from it all, escape onto the eight hundred miles of hiking trails.

On the Appalachian Trail , however, you can now only camp in designated areas, caged in behind iron bars to keep out the bears. Hikers intending to stay out overnight will need to obtain backcountry permits , available free from visitor centers (except in Cades Cove).

The park also has ten developed campgrounds , of which the three most popular - Cades Cove, Elkmont and Smokemont - are always fully booked. Reserve in advance (tel 1-800/365-CAMP) if you want a space in summer or fall. For enquiries contact the park headquarters (tel 865/436-1230).

On Saturday, from dawn until 10am, the Cades Cove loop is reserved for cyclists . Bikes can be rented at the Cades Cove Campground (tel 865-448-9034).