Sixty years ago today, a small military observation plane flew over the Horse Heaven Hills and along the Columbia River. It was an unusually warm day with a chinook wind blowing under sunny skies.

Lt. Col. Franklin Matthias glanced through the Plexiglas floor in the cockpit, and knew at once he had found the site for the largest construction project of World War II.

Hanford.

It was a decision that would change the Mid-Columbia in ways few could imagine. And the change would come almost overnight.

Several events could be considered Hanford's beginning: Glenn T. Seaborg's successful efforts to create plutonium 239 in 1941, the first controlled nuclear chain reaction in December 1942, or acquisition of the first tract of land in March 1943.

But Matthias' flight was the first link between the Mid-Columbia and events unfolding in nuclear physics laboratories. It was a whirlwind marriage.

The day Matthias' little plane flew along the river, the farming towns of Hanford, Richland and White Bluffs had a combined population of about 1,200. Months later, the federal government evicted everyone, telling them only that their land was needed for the war effort.

During the next two years, 157,000 people came and went as construction workers assembled a remarkable weapons plant, sometimes working from plans drafted only hours earlier.

The peak population in Hanford's tent and trailer city at any single time during construction of the Hanford project reached 51,000.

Until the bomb dubbed Fat Man was dropped on Nagasaki in August 1945, all but a handful of people remained ignorant of the purpose behind the Hanford effort.

In reality, even the best informed insiders were uncertain where this marriage between the isolated Washington desert and cutting-edge physics might lead. Certainly, no one anticipated what the next 60 years would bring to the project and the Tri-City community.

"When the Corps of Engineers started its work, its job was simply to build and operate the production plants," Gen. Leslie Groves, head of the Manhattan Project, wrote in his memoirs.

"The problems involved in the development of the bomb and its delivery were for the time being largely ignored. Nor was the full magnitude of the project generally appreciated.

"No one thought of it as entailing expenditures running into billions of dollars. Not until later would it be recognized that chances would have to be taken that in more normal times would be considered reckless in the extreme.

"Not until later would it become accepted practice to proceed vigorously on major phases of the work despite large gaps in basic knowledge.

"Not until later would every other consideration, whether the advancement of knowledge for the sake of knowledge or the maintenance of friendly diplomatic relations with other powers, be subordinated to achieving the project's single overriding aim.

"Not until later would all concerned grow accustomed to the idea that, while normally haste makes waste, in this case haste was essential."

In truth, it wasn't until after World War II that most of Hanford's story unfolded. The plants made to win one war grew into a massive Cold War complex, producing 53 tons of plutonium before Hanford's last defense reactor ceased operations in 1987.

It's a story still being written today, as a work force that fluctuates between 10,000 and 15,000 men and women works on cleaning up the Cold War's nuclear and toxic mess.

It's all part of a continuum that shaped a century, first by producing a bomb that helped end a war, then by fueling an arms race that hastened the fall of communism.

The story may never have a final chapter. Even after cleanup is completed, Hanford will be left holding radioactive materials that will take tens of thousands to millions of years to decay away.

But we know how it began: with one lonely flight.