The view from this hill changed greatly over the years. In the 1930s, this was the most spectacular cactus forest in Arizona, but these aging saguaros were near the end of their lives. Mild weather in the late 1800s may have nurtured this forest of giants. Those who created Saguaro National Monument in 1933 believed the forest would last forever. In February 1937, a cold front brought record low temperatures to Tucson, and a few years later saguaros began to die at an alarming rate. For a decade, scientists and the public struggled with the "cactus blight." After another killing freeze in 1962, researchers realized that temperatures below freezing for more than 20 hours could kill saguaros. Before 1980, almost no young saguaros could be found here, and predictions of doom were made that the last saguaro would die in the 1990s. In 1979, the National Park Service acquired all grazing rights in the Cactus Forest, and after decades of trampling by cattle, young saguaros began to sprout under palo verde and mesquite nurse trees. The trend toward renewal continues today.