Ever since the real Grand Canyon became an Arizona geological tourist attraction, other areas have been promoting their own grand canyons. Truth be told, there are many impressive chasms around the country. The gorge of Pine Creek, in north-central Pennsylvania, is billed as "Pennsylvania's Grand Canyon" and is preserved as a pair of state parks. I've just added it to my gallery of Pennsylvania Geological Attractions and Destinations.
There is also the "Grand Canyon of the East" at New York's Letchworth State Park, the Grand Canyon of the Pacific or Waimea Canyon in Hawaii, the Grand Canyon of the Yellowstone in Wyoming and the Grand Canyon of the South between Virginia and Kentucky. Not to mention the Black Canyon of the Gunnison in Colorado, which is grand in all but name.
Courtesy fishhawk of Flickr via Creative Commons license