Populus tremuloies, the Quaking Aspen or Trembling Aspen, is a deciduous tree native to cooler areas of North America, with the northern limit determined by its intolerance of permafrost. It occurs across Canada in all provinces and territories (with the possible exception of Nunavut). In the United States, it occurs at low elevations as far south as northern Nebraska and central Indiana. Farther west, it grows at high altitudes as far south as Guanajuato, Mexico. In the western United States, this tree rarely survives at elevations lower than 1,500 feet due to the mild winters experienced below that elevation, and is generally found at 5,000-12,000 feet.