On Oct. 28, 1984, United Airlines added four states -- Wyoming, North Dakota, West Virginia and Mississippi -- to its route system. That in itself was not a significant event, but the four new destinations meant that United could claim it was the first airline to fly to all 50 states.

To commemorate this singular achievement in airline service, United tried to think up a special promotion. Actually, it was more of a challenge than anything else.

United challenged its 2 million frequent-flyer passengers (members of its "Mileage Plus" program) to fly 50 states in 50 days. The passenger had to fly to or from all 50 states between Oct. 28 and Dec. 16, 1984.

Anyone determined enough (or crazy enough) to actually get to all the 50 states would be given a special gold pass entitling them to unlimited free first-class flying on United anywhere in the United States -- including Alaska and Hawaii -- for one year.

Before announcing the promotion, United tried to figure out if anyone would, in fact, take them up on it. The airline did internal computer projections that indicated that a few might try to fly to all 50 states, but that it would cost each person a minimum of $16,000 and require a tremendous amount of flying time.

"We really had no idea if anyone would do it," says United spokesman Joe Hopkins. "But it was a fun idea."

And so, last fall United sent out a mailing announcing the promotion to all of its 2 million Mileage-Plus participants.

Within days of the mailing, a surprising number of people started flying United to, well . . . everywhere.

In fact, 78 intrepid Americans managed to complete the challenge in the allotted 50 days. The 69 men and nine women came from 25 states and ranged from golf pro Craig Stadler to a paraplegic from Whitmore Lake, Mich., an NBA referee and a Catholic priest.

Surprisingly, only a few folks spent anywhere near the $16,000 United had projected. Many used ingenious itineraries and ticketing to save money. Some used buses, trains and rental cars to get between cities served by United.

A winner from Scottsdale, Ariz., used a 3 percent government loan to buy his ticket. Another flew to Hong Kong and purchased a "Visit USA" United ticket for just $860. (This is a little-publicized ticket sold only overseas to foreign nationals planning a trip to the United States, but is also available to savvy Americans who know the rules don't prohibit their buying them as well. The ticket purchased by the winner provided unlimited travel within this country for 60 days. The current United version of that ticket now permits up to 45 days travel, depending upon price paid, and it is no longer unlimited.) "That guy really outfoxed us," says United's Hopkins. "Luckily he was the only one who thought of it."

Time, of course, was of the essence, and getting to and from some United cities wasn't always easy.

The station agent for United Airlines in Casper, Wyo., couldn't quite figure it out. Once each morning, Flight 455 would arrive from Denver. As scheduled, it would deplane passengers, wait 30 minutes and then board new passengers for the return flight to Colorado.

A few times each week late last year, a number of passengers arriving on that flight would simply get off the 727, wait 30 minutes, and get right back on. It made no sense, unless you were trying to fly to all 50 states.

Many of the marathon players had to do more than just plan their flights. A winner from Snohomish, Wash., used a seven-hour layover in Allentown, Pa., to go to a local laundromat to do his wash.

Other 50-state travelers used the time to finish some writing projects. One winner, Dr. Michael Brein of Hawaii, says he will now write a book of travel adventure stories based on his marathon experience.

Another winner simply wrote postcards from each of the 50 states and sent them to John Zeeman, United's senior vice president, as additional proof that he had, in fact, been there.

Nancy Stonington, an artist and gallery owner from Anchorage, Alaska, did 50 watercolor paintings, one of each of the 50 states she went to, miniature landscapes inspired from the view from her airplane window of each flight she flew.

"When I read about it," she says, "I talked about it with my husband. We thought it would be fun to do this together." Stonington and her husband, Bob Waldrop, a mountaineering guide for the Brooks Range in Alaska, quickly became experts on United's flight schedule. "We wanted to complete all our travel in two weeks, do it the cheapest and most time-saving way."

Once the couple started on the marathon, they hardly stopped. On one particular day, they flew to seven different states. "It was exciting," she says. "At some places we only had five-minute connections between flights. That's when we quickly learned which were the great airports."

One of the marathon rules was that the trip begin or end at each individual state -- taking a flight that stopped at one or two states en route to its final destination did not qualify.

"That made for some interesting scheduling," Stonington laughs. "We'd fly to Dulles Airport in Washington, drive to Baltimore and take another United flight. Then we'd fly to Burlington, Vt., drive to Manchester, N.H., and take another United flight to some other state."

The Stonington-Waldrop duo made Hawaii their last stop. "We needed a rest," she says. The couple was able to complete the 50-state challenge for a little less than $6,000 each. "It was worth it," Stonington says. "In coach air fares alone," she claims, "I figure I'll save $30,000 in the next year. An added bonus will be that I'll be flying first class."

A Catholic priest also completed the 50-state itinerary, traveling incognito because he did not want to cause problems with his bishop.

"I always had a goal to set a foot in each of our 50 states," says Andy Sim, director of the Chicago Junior School -- a private day and boarding school in Elgin, Ill. "I'm grateful that it came at the right time, when I had vacation time coming."

On Nov. 1 Sim began the marathon in Chicago and on Nov. 24 he finished in Honolulu. He did it mostly on weekends and eight weekdays of vacation time. He covered all six New England states in one day.

The three top executives of the Boyd Group, a nationwide marketing company based in Knoxville, Tenn., completed the marathon.

Tom Boyd says that it cost himself and another employe $8,000 each, but a more economical employe only spent $6,000. Actually, Boyd says he spent only $3,000 on United flying only one-way, not round-trip between cities. Since a requirement was that all one had to do was fly into or out of a state on United, he used trains, rental cars and cabs to make essential connections.

"We usually spend $30,000 to $40,000 apiece for business travel in one year. This year we will probably save $250,000 since we have a year of free travel."

While completing the 50-state trip, Boyd says he "learned that airlines have lots of deals if you just check them out. Business people get rooked. I also learned patience. You just get on the plane. If it doesn't land on time -- who cares."

He also learned about instant jet lag -- "After two or three days you don't know where you are" -- and about the repetition of airline food. "I do wish airlines would consider business travelers when planning menus," he laments. "I was tired of eating identical food for 17 days."

One meal Boyd and the other winners remember is the special awards dinner United threw for them in late March in Chicago. Each was flown in and presented with the special free first-class travel card.

A man from Rockford, who did his 50 states in 34 days, boasted that he had chalked up 30,000 miles in the air and now plans to fly even more. "The most amazing thing," he says, "is that when I started all this I was actually afraid to fly." After receiving his gold card, the first place Tom Bestor -- a media relations officer for GTE Sprint in San Francisco -- visited was Columbus, Ohio. Next on the agenda is Vermont, then off to buy live lobster from Maine or Boston, visit his uncle in Kansas City, Mo. Then, he says, "maybe I'll go and see Hawaii -- at least this time I'll stay for more than an hour."

Needless to say, the United Airlines promotion was a huge success. But don't count on United doing something quite like this again. "There's no way to put a dollar cost on the promotion," says United spokesman Chuck Novak. "But it achieved what we wanted by making Americans conscious of us being in all 50 states. On that score, we think it was very successful."

One last note: At the dinner, the winners agreed that they will meet again later this year to discuss their latest flying experiences on United. "It really won't be a problem figuring out where to meet," says Tom Boyd. "After all, the flight will be free."