Tumbleweed was assembled in an area of heavy pedestrian traffic along the bank of the Willamette River in Portland, Oregon. Passers-by, attracted by the spectacle, organically became involved in the building by tying and winding long strings of balloons around the delicate bundle. Once assembled, the impromptu contributors and audience followed in an ad hoc procession to the water’s edge, at sunset, to witness its release onto the water, and watch it slowly somersault downriver.