Iron wheels clicking again, renewed whistles shrill and melancholy, mahogany passenger cars with brass appointments and leather seats, all recall an age when big business and big politics were carried on in the rolling stock. In the age of steam, the American dream came true. The railroad grew up with America. The principal artifact of the Industrial Revolution, the steam locomotive, wearing all its movable parts on the outside, has a permanent place in the hearts of Americans. In 1950 there were 47,000 steam locomotives in the country. Today there are only 3,500. Although the iron horse is a transportation anachronism, steam railroads are being restored, not so much to link separate places as separate centuries. They have b ecome popular attractions for vacationers who may remember what the old days of train travel were like, and for youngsters who have never ridden on a train.
Now nearly 80 steam trains operate passenger service, from 15-minute, one-mile rides to daylong excursions on original mainline track or logging and mining routes through rugged country sometimes inaccessible by other means. Nearly every state has a steam train listed in the Passenger Service Directory (available for $6 from Empire State Railway Museum, Box 666, Middletown, N.Y. 10940). From east to west, here are 10 of the longest, most authentic, and most spectacular rides. Prices given are for adults ; children have reduced fares.
Mt. Washington Cog Railway: Locomotives built between 1870 and 1908 with tilted boilers to accommodate a steep incline have pulled passengers up New England's highest mountain (6,293 feet) for more than a century. Three miles of the three-hour trip are on 1869 wooden trestles with an average grade of 25 percent, or 1 foot in 4. The route goes from red spruce forests of the temperate zone to wildflowers of the alpine zone. Schedules, May to October, are subject to weather conditions at the s ummit. $22. Mt. Washington, N.H. 03589. (603) 846-5404.
Valley Railroad: A 12-mile, one-hour trip over a former New Haven branch line travels along the Connecticut River, through the Essex Valley, passing farms, villages, salt marshes alive with waterfowl, marinas, even a turreted castle. Passengers can connect to a river cruise. Some cars are open excursion cars called Wyatt Earps; one is an elegantly restored 1925 Wallingford Pullman parlor car. May through October, with limited service spring and fall. $6. Railroad Avenue, Essex, Conn. 06426. (202)
Strasburg Railroad: America's oldest short-line railroad began service in 1851. Once a freight handler, it's now puffing passengers past Currier & Ives farms of Pennsylvania Dutch country. Weekends mid-March through mid-December; daily May through October. $4. PO Box 96, Strasburg, Pa. 17579. (717) 687-7522.
Cass Scenic Railroad: For 60 years this logging railroad hauled lumberjacks from the company town of Cass, W.Va. (now a National Historic Site) deep into the Appalachian Mountains. For climbing Bald Knob Mountain at 4,862 feet, there are two dramatic switchbacks that look like a zigzag in the track. The train goes beyond the intersecting rails; when the switch is thrown, it reverses and begins its sharp climb backward. The process is repeated at the other zigzag to send the train on its way. The ful l 22-mile, 41/2-hour round trip to the summit is $9.50; a shorter version is $7. May through October. Cass, W.Va. 24927. (304) 456-4300.
Cuyahoga Valley Line: The nation's only steam railway providing service between two major cities, this 61/2-hour round trip travels along the Ohio-Erie Canal to connect Cleveland and Akron, 55 miles apart. Schedules are listed with Amtrak. Fares range from $7 to $20. Saturdays only June through October. Reservations recommended. PO Box 49, Peninsula, Ohio 44264. Cleveland phone (216) 468-0797. Akron, (212) 657-2474.
Mid-Continent Railway Museum: With utter authenticity, turn-of-the-century locomotives chug five miles through the fertile Baraboo River Valley past the ghost town of La Rue and on to an abandoned quartzite quarry. It passes so close to a purple quartzite bluff that the staccato sound of the steam engine echoes off the wall. May to October, plus a Snow Train the third full weekend in February. $5.50. North Freedom, Wis. 53951. (608) 522-4261.
Durango & Silverton Narrow Gauge Railroad: Formerly part of the Denver & Rio Grande Railroad built in the 1880s to connect the mining center of Silverton to the entire narrow-gauge system, this 90-mile round trip takes 91/2 hours, including a lunch stop in Silverton. As early as 1910, tourists traveled this dramatic route through the remote wilderness and undulating foothills of the San Juan National Forest, through jagged terrain with sharp vertical drop-offs to an alpine valley. Much of this specta cular scenery is accessible only by horseback, on foot, or by this line. Year round, but with the winter route ($21) shorter than the summer route ($28). Reservations by mail recommended. 479 Main Avenue, Durango, Colo. 81301. (303) 247-2733.
Cumbres & Toltec Scenic Railroad: Spiked down in 1880 with the ambitious aim of connecting Denver with Mexico City, the C&TS was originally a branch line for mining camps in the San Juan Mountains. The 64 miles of track are part of a once-vast network of narrow-gauge lines which laced together commercial outposts of the Rocky Mountains. The route snakes over Cumbres Pass (10,015-foot elevation), traverses high-country grassland and alpine meadows, spans gulches 137 feet high, and follows Toltec Gorge and Phantom Curve (where bizarre volcanic formations loom over the track). The route is divided into two trips: The Colorado Limited (Antonito to Osier, Colo.) and the New Mexico Express (Chama, N.M. to Osier, Colo.) with round-trip fares of $25. Traveling both routes with van return to point of origin is $39.50. Daily, June through October. Reservations required. PO Box 789, Chama, N.M. 87520, (505) 756-2151; or PO Box 668, Antonito, Colo. 81120, (303) 376-5483.
Oregon Pacific & Eastern Railway: Situated 20 miles south of Eugene, the OP&E, still an active freight line, takes summer passengers on a 35-mile, two-hour trip through Oregon forests. The 1914 steam locomotive, nicknamed ``The Goose,'' provides quantities of hissing, chugging, and wheezing as it traces historic routes to mining districts and sawmills. Passengers ride in modern coaches. June 15 through Labor Day. $7. PO Box 565, Cottage Grove, Ore. 97424. (503) 942-3368.
Railtown, 1897 State Historic Park: The Cannonball steam engine, originally serving mining and logging sites, now puffs 12 miles through the mother lode country of the Sierra foothills. Weekends and holidays, July through September. $7. PO Box 1250, Jamestown, Calif. 95327. (209) 984-3953.