Once a year, the ghost town known as one of the most toxic in the world comes alive again. People flock to the streets, there’s lights and chatter and laughter, but as soon as the day is over, the people leave the confines of the city and the streets fall silent once more.

Picher, Oklahoma was once a mining town. Lead and zinc were hauled upwards from the earth and those who worked in the mines brought their families to this little slice of paradise in the middle of nowhere. The town sprung up almost overnight — but what was waiting under the earth would eventually see it destroyed.

By 1920, the town was home to just under 10,000 people and production in the mine reached its peak.

Tunnels crept below much of the city’s infrastructure and gigantic mountains of chat (mining waste that has been hauled to the surface) sat across the town in hulking piles. Children used to play on and around the toxic piles, and kids from Picher were known derogatorily by outsiders as ‘chat rats’. The material was even used to patch roads.

However, after 1926, much of the prosperity was over. The decrease in mining activity led a lot of families to leave town and by the 1960s, the city only had 2,553 residents left. By 1967, all mining had stopped — and importantly, water pumping from the mines stopped too.

This meant that water flooded the mine shafts and became contaminated with sky high levels of heavy metals including lead, zinc, iron, nickel and cadmium. Then, this water leached into the creeks around Picher.

By the mid-90s, Indian Health Service were concerned enough to blood test the children living in the town and found that 35 percent had concerning levels of lead in their blood. In 2004, tests on the soil of daycares, schoolyards and playgrounds found high levels of lead and other heavy metals — enough to convince the Environmental Protection Agency and the state of Oklahoma to issue a mandatory evacuation and buy out the entire town.

It wasn’t just the toxic soil that meant Picher had to be abandoned. When the mining had ceased, all 1,400 cavernous spaces beneath the town had been left open. Over time, the contaminated water deteriorated the supports, and the entire town is now at risk of caving in and being swallowed up into the toxic sludge that lies underfoot at any moment.

The slow creep of the residents had begun, and by 2013, the municipality had officially dissolved. The last remaining residents who had tried to stay in the town took buyouts after a 2008 tornado destroyed 160 homes and killed six people. Now, the city is considered too toxic to live in. But every year, those who were forced to leave their homes come back for one evening.

In early December, there is a Christmas parade through Picher Oklahoma, and residents who were forced out come back on their own terms. They drink, eat and sing songs amid the toxic wasteland — and they wear sweatshirts emblazoned with ‘Chat Rats’ — the old insult reclaimed and worn as a badge of honour.