MASSENA, N.Y. (AP) - Working 90 feet above the ground, pouring buckets of concrete that would harden into a 195-foot-high dam the length of 11 football fields, a teenage Frank Wicks knew even then he wasn't on just another job.
''We had a real sense of excitement. At the time it was going on, it was the world's biggest construction project. We knew we were part of history,'' said Wicks, who worked on construction of the St. Lawrence Seaway after graduating from Massena High School in 1957.
''I remember growing up, people were always talking about it. Now, it's kind of been forgotten,'' said Wicks, now 70 and a mechanical engineering professor at Union College in Schenectady, N.Y.
Hailed as one of North America's top engineering marvels and one of the most important public works of the 20th century, the $470 million project - of which Canada funded $336 million and the U.S. about $134 million - linked the Great Lakes interior industrial hubs to the Atlantic Ocean.
It was branded by some as obsolete before it was even finished and today is an obscure footnote in history for many Americans. Yet for a half century it was the defining issue in American-Canadian relations and even now is regarded as one of the country's most durable deeds of diplomacy.
Stretching 265 miles along the U.S. border with Canada from Montreal to Lake Ontario, the Seaway replaced the river's old 14-foot-deep, 30-lock canal system with 27-foot-deep channels, 15 locks and an international hydrodam.
Since it opened in 1959, more than 2.5 billion tons of cargo - mostly grain, iron ore and steel - valued at more than $375 billion have passed through the Seaway.
The Moses-Saunders dam provides low-cost power to more than 1 million consumers in the two countries.
Queen Elizabeth II, President Dwight Eisenhower and Vice President Richard Nixon came to Massena to christen the shipping route. Fifty years later, there will be no royal or presidential appearances during a weekend of 50th anniversary events that began Thursday - possibly a statement about the Seaway's present and future.
As the global economy has faltered, freight levels have dropped for the past two years and cargo levels were down 40 percent for the first two months of the current shipping season, according to Seaway officials.
''Over its time, it has played a major role in the economy of the Great Lakes. In the future, it can still be a very relevant feature to the region's economy, even if it's just one of many features,'' said Collister Johnson Jr., administrator for the St. Lawrence Seaway Development Corp., which runs the American portions of the system.
The Seaway was created between 1954 and 1959 by taming a 44-mile stretch of rapids, temporarily diverting the St. Lawrence River and flooding six Canadian villages. More than 22,000 workers excavated 360 million tons of earth and poured 6 million cubic yards of concrete, completing the project three years ahead of schedule.
The idea of northern deep-water shipping route was first raised by a joint U.S.-Canadian commission in the 1890s. For the next half-century, U.S. and Canadian politicians debated its merits.
Cold War-era American politicians were finally won over by the Seaway's national security potential - an inland waterway protected ships and submarines in the event of an attack - and its potential for fostering industrial growth in America's heartland, while Canada desperately needed the power from the dam, said Claire Puccia Parham, a history instructor at Siena College in Loudonville, N.Y., and author of the recently published ''The St. Lawrence Seaway and Power Project: An Oral History of the Greatest Construction Show on Earth.''
''It's in an isolated location and it basically sits there doing nothing spectacular. Most Americans are unaware of the Herculean accomplishment the Seaway was in terms of engineering, construction and diplomacy,'' said Parham, who interviewed more than four dozen former workers for her book, including Wicks.
The Seaway is credited with creating and preserving millions of jobs in Canada and the Great Lakes states but it did little to transform New York's North Country.
For a five-year span during its construction, the project brought widespread prosperity to the region. The influx of outsiders also brought a fleeting jolt of cultural awakening and worldliness to the less sophisticated, tradition-steeped rural communities.
''Locally, it turned out most benefits were short-lived,'' said Brian Chezum, a labor economics professor at St. Lawrence University in Canton, N.Y. ''The Seaway was viable as a commercial venture largely because of the benefits generated by hydropower. This stands in sharp contrast to the estimates that were used to support the project which generally expected a much larger impact from navigation.''
Although an engineering milestone, the project had its blemishes. The locks were supposed to be 100 feet wide, but the American government capitulated to Canadian shippers and kept the locks at 80 feet. That meant the transoceanic freighters would have to unload in Montreal, and then pay local companies to take their cargo the rest of the way on smaller ships.
''It could have been more than it was. People said it was obsolete the day it was completed because it wasn't big enough for oceangoing vessels,'' said Parham.
On the positive side, not allowing transoceanic vessels into Lake Ontario likely preserved The Thousand Islands region as a recreational destination.
''Tourism wasn't something they talked about in the 1950s, but it has been maybe the one lasting benefit for the local region,'' Chezum said.
While the Seaway has had a productive past, officials concede its future is uncertain.
This year marks the beginning of the biggest infrastructure investment in the Seaway's history. In March, Congress nearly doubled the Seaway's annual budget to $32 million. The extra money, like a similar Canadian investment, is part of a 10-year project to modernize and maintain the system.