Editor’s Note: This article is part of our “Hidden Washington” series, where we highlight the fascinating places, forgotten history, and little-known stories hiding in plain sight across the Evergreen State.
Most Washington residents have heard the name Hanford. Few have any idea what it actually is.
Hidden in the high desert northwest of the Tri-Cities, along a remote stretch of the Columbia River, sits the sprawling Hanford Site — a federal nuclear reservation covering roughly 580 square miles.
The site helped create the atomic bombs that changed World War II, fueled the Cold War nuclear arms race, and remains one of the most contaminated places in the United States.
Today, much of Hanford sits empty and off-limits to the public. Yet beneath the desert floor, millions of gallons of radioactive waste remain stored in aging underground tanks.
Welcome to the Hanford Site: Washington’s most dangerous place that almost nobody visits.
A Secret City Built For War
In 1943, the federal government arrived in southeastern Washington with a mission that would change history.
As part of the Manhattan Project, the top-secret effort to develop the world’s first atomic weapons, officials selected a remote stretch of desert near the small farming communities of Hanford, White Bluffs, and Richland.
Residents were forced to leave their homes with little notice. Entire communities disappeared.
In their place, the government built a massive industrial complex dedicated to one purpose: producing plutonium for nuclear weapons.
At its peak, tens of thousands of workers flooded into the region. Most had no idea exactly what they were building.
Security was intense. Questions were discouraged. Secrecy was everything.
The Plutonium That Changed The World
The Hanford Site became home to giant nuclear reactors unlike anything the world had seen before.
Among them was the B Reactor, the first full-scale plutonium production reactor ever built.
The plutonium produced at Hanford was eventually used in the atomic bomb dropped on Nagasaki, Japan, in August 1945.
The bombing helped bring World War II to an end, but it also ushered in the nuclear age.
For decades afterward, Hanford continued producing plutonium as the United States and Soviet Union raced to build ever-larger nuclear arsenals.
By some estimates, Hanford produced a majority of the plutonium used in America’s nuclear weapons program during the Cold War.
What Was Left Behind
Producing plutonium created an enormous amount of radioactive waste. For years, much of that waste was stored in underground tanks, buried trenches, and disposal sites scattered throughout the reservation.
When the Cold War ended, the federal government faced a staggering problem.
Hanford had become one of the most contaminated nuclear sites in North America.
Today, 177 underground waste tanks remain on the site. Together, they contain tens of millions of gallons of radioactive and chemical waste.
Some tanks have leaked. Others are decades beyond their original design life.
The challenge of safely treating and storing that waste continues to this day.
America’s Largest Environmental Cleanup
Hanford is no longer producing plutonium.
Instead, it has become the focus of what is often described as the largest environmental cleanup project in the United States.
Thousands of workers spend their days monitoring contamination, removing hazardous materials, demolishing aging structures, and preparing radioactive waste for long-term storage.
The effort has already cost billions of dollars.
Cleanup work is expected to continue for decades.
Some experts believe portions of the project could extend well into the second half of this century.
Can You Visit Hanford?
Surprisingly, yes.
Although most of the reservation remains closed to the public, visitors can tour portions of the site during designated programs.
The biggest attraction is the historic B Reactor.
Now preserved as part of the Manhattan Project National Historical Park, the reactor offers a rare look inside one of the facilities that helped launch the nuclear age.
Walking through the building feels less like visiting a museum and more like stepping into a time capsule from one of history’s most consequential scientific projects.
The rest of Hanford remains heavily restricted. Many areas can only be accessed by authorized personnel.
A Place Most Washingtonians Never See
For all of its historical importance, Hanford remains largely invisible to the rest of the state.
It receives only a fraction of the attention given to Seattle landmarks, Mount Rainier, or the San Juan Islands.
Yet few places in Washington have had a greater impact on world history.
The site helped shape the outcome of World War II, fueled decades of Cold War tensions, and continues to influence debates about nuclear energy, environmental cleanup, and national security.
Most drivers speeding through the Tri-Cities area never realize they are passing one of the most significant places in American history.
Hidden behind fences and miles of desert, the Hanford Site remains a reminder that some of the biggest stories in Washington happened far from the state’s largest cities.
And even now, more than 80 years later, the work isn’t finished.
Want to learn more or see tour information? Visit the official Hanford Site and Manhattan Project National Historical Park pages.
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