When John Henry “Doc” Holliday headed to Denver, Colorado, in 1882, he was escaping murder charges for his involvement in a shootout at the O.K. Corral. But he stayed in the state not for crime, but for the sake of his lungs. Holliday suffered from tuberculosis, and at the time everyone knew that Colorado was the best place for so-called “lungers” to rest and recover.

In the 1800s, tuberculosis was the nation’s leading cause of death. The “White Death” was much feared and little understood. Since there was no vaccine or antibiotic available to fight the disease, the only hope many tubercular patients had was to move from humid, stormy eastern locations in pursuit of the west’s drier, higher, sunnier skies—all of which Colorado had in abundance.

The influx of TB patients that streamed into Colorado helped put the state on the map. At its heyday as a consumption sanctuary, an estimated one in three Colorado residents suffered from tuberculosis, the state was home to an unusual number of physicians, and a third of all Colorado deaths were from TB compared to a national average of one in 10.

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Also known as consumption at the time, tuberculosis is caused by a bacterium that, when breathed in, can cause weakness, chest pain, coughing, shortness of breath and other symptoms. (Today, only three people per 100,000 suffers from TB in the United States.)

Previously, Colorado had been known as a haven for Wild West criminals and miners, thanks to a series of gold and silver rushes that made it an attractive destination for fortune hunters. But while its rudimentary towns and camps were rife with drunkenness, gambling, prostitution and crime, the negatives of Colorado’s unsavory reputation as an uncivilized, crude backwater were outweighed by the positives of its climate.

Physicians in the 19th and 20th centuries believed that fresh air, high altitudes and abundant sunshine could cure all kinds of ailments, and Colorado had plenty of all three. Although their beliefs about TB were not entirely medically sound, they were kind of right in this regard: Fresh air does prevent TB from spreading, and the high altitude stops TB bacteria from spreading as rapidly through the lungs. But at the time, doctors believed the contagious disease to be hereditary, and thought it was transmitted through the air instead of through physical contact.

Beginning in the 1860s, ill people began pouring into the future state to take the fresh air cure. Denver’s first facility for tubercular patients was built in 1860, just two years after the city was founded. Colorado Springs and Boulder soon followed suit, and entire cities began to spring up around TB treatment facilities.

These resort-like health spas were places to relax, rest and often die. They had names like Montcalm, Sunnyrest and Cragmor. Boulder’s most prominent sanitarium allowed “guests” to relax with health spa-like diets, view intricate oil paintings and listen to a live orchestra. The health hotels featured large porches on which wealthy guests could take in sun, breathe fresh air and enjoy mountain views. At the Hygiene House in the town of Hygiene—named after its resort—they sipped mineral water (thought to have curative properties), ate rare plants and sat outside for 10 hours a day, even during blizzards. The more opulent tuberculosis facilities even bred their own elite social scenes and attracted famous patients from all over the world.

Not everyone could afford these plush resorts, though, and some sanatoriums were little more than a collection of tents. Soon, Colorado had a homelessness problem brought on by desperate patients who bought one-way tickets even though they were unable to pay for treatment. In Denver, Francis Weisbart Jacobs founded an entire hospital, the National Jewish Hospital for Consumptives, to provide free treatment for those patients. (Today, the hospital is a leading research and treatment facility for lung-related ailments.)

When scientists discovered the TB bacterium in the 1880s, they did not yet realize that infection could only be spread by close contact with an infected patient’s breath. But the knowledge that TB was contagious made Coloradans increasingly suspicious of tubercular tourists. Spitting was outlawed and women were encouraged to shorten their skirts lest they spread the disease with dust from city streets.  

TB patients were stigmatized in newspaper articles and public life. “TWO BROTHERS ARE INSANE,” blared one 1906 headline in the Denver Post. The article told of two “victims of the White Plague” who came to Denver from Cincinnati, lived in a tent, and grew increasingly weak. “When they were found in their squalid tent,” the reporter continued, “their condition was frightful.” The Colorado legislature even debated a law to require TB patients to wear bells around their necks.

Eventually, the TB epidemic—and the heyday of the consumption sanatorium—came to an end when, in the 1940s, antibiotics became an effective treatment for the disease. By then, tuberculosis had transformed Colorado. Places like Colorado Springs went from little-known backwaters to thriving cities, their streets and schools improved by bequests and gifts from wealthy patients. Lungers like Denver mayor Robert Speer and Senator Edwin Johnson left marks on the state’s infrastructure and national prominence. And many sanitariums morphed into the state’s most respected hospitals.

Colorado may no longer be known as the “World’s Sanatorium,” but it owes much of its modern prosperity to a now rare disease.

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