NASHVILLE, Tenn. — It’s not every day you see houses towed behind pickup trucks, making their way through the center of town. But a few months ago, homes in Nashville, Tennessee began that journey, delivering security and shelter to those who needed it most.

It’s part of a unique project called the Sanctuary. In 2012 the Green Street Church of Christ, which has long been a service provider to the homeless, started offering safe refuge behind the church’s fence to homeless campers. The church’s deacon, Caleb Pickering, says that before he knew it 20 tents were in its backyard. Three years later, Nashville pastor Jeff Carr approached Pickering and the Green Street Church with an idea: Convert the tents into microhomes.

By all accounts, Nashville is a thriving city, drawing tourists and new residents in huge numbers. Forbes named it one of America’s 20 fastest-growing cities in 2015. But according to advocates, that popularity is also driving up the homeless population, with fewer options for low-income housing.

It’s estimated there are roughly 600,000 homeless in the United States. The official numbers for Nashville are around 2,300, but local outreach organizations believe the number is three times that, totaling close to 8,000 men, women and children.