It's hard to pinpoint when exactly the modern day designer tree house revival started, but there are a few notable people that can be credited for the renaissance.
In 1991, Michael Garnier opened a bed and breakfast in the branches near Cave Junction, Ore., called the Out 'N' About Tree house Treesort. In 1997, Garnier founded the annual World Tree House Association Conference at his "treesort" to create a place for tree house builders and enthusiasts to come together and share their ideas. A mechanical engineer suggested that a tree house platform could be perched on a steel cuff and secured with a steel bolt, in lieu of pinning beams to the tree. Over the next two years, conference participants came up with a cuff and bolt design that holds up to 8,000 pounds (3.628 tons). It was named the Garnier Limb.
Another major player in tree house circles is Pete Nelson, known as "Mr. Tree House" to his friends. Nelson is a master builder and author of several books about tree houses. He co-founded Tree House Workshop with partner Jake Jacob, and they've been building custom tree houses since 1997. Nelson and Jacob integrate this reclaimed wood into Tree House Workshop projects, and they are known as the go-to builders for groundbreaking arborial designs.
Bill Compher is the proud owner of the vacation destination Cedar Creek Tree house in Mt. Ranier, Wash. The main cabin, which was built in 1998, is perched in the trees of a lush rainforest, 50 feet (1,524 centimeters) off the ground in a 200-year-old giant cedar tree. In 2001, Compher added a tree house observatory that he built himself because he couldn't find anyone else to do it. Compher and his son added spiral staircase around the trunk of the tree to provide access to the observatory and named it "Stairway to Heaven." In 2004, a brightly colored bridge was hoisted to connect the two tree house structures.
Corbin Dunn gets the prize for having the largest habitable tree house in the United States. He started building it when he was 20 years old, and he lived in it for five years in the 1990s. The house came tumbling down in early 2009, leaving a kitchen sink hanging by the pipes. Fortunately, Corbin had moved on by that time.