In 1906, President Theodore Roosevelt created the Grand Canyon National Game Preserve on the Kaibab Plateau in northern Arizona. Between 1907 and 1923, cattle grazing was greatly reduced, mule deer hunting was eliminated, and predators were killed. Over 800 cougars, 20 wolves (most had already been killed in the 1800s), and 7000 coyotes were trapped or shot. In response, the mule deer herd began to increase: By 1915, deer numbers were estimated at 25,000; 50,000 by 1920; and 100,000 by 1923. The removal of the livestock and predators, and the cessation of hunting in 1907 .