Tonto Natural Bridge is a geological formation in the Pinal Mountains of northwestern Arizona, United States. It consists of a large convex limestone slab with an exposed cristobalite core, set on top of another rock ledge the Lower Rock Shelton Formation – within Apache-Sitgreaves National Forest. The natural bridge rises some 550 feet (170m) above the stream below and spans 250 feet (76m). Its exposure time is short compared to other areas of the forest; it collapsed following heavy rains in June 2005. Before its collapse, the area was accessible by automobile via State Route 88, which intersects the north end of the park. Access now requires hiking or taking the bus from Springerville, about 12 miles (19km) away.
In 1970, the state designated 1,300 acres (530ha), including the natural bridge site, as Tonto Natural Bridge State Park. However, due to budget cuts, the park remains unstaffed except for limited maintenance. Unofficially, this makes it one of the most visited unguarded public lands in the country. According to legend, the natural bridge served as a hideout for two notorious stagecoach robbers, Frank and Jesse James. Frank died in a gunfight with police while trying to escape from the scene, but Jesse lived long enough to be captured. He was tried, convicted, and sentenced to death, but his sentence was commuted to life in prison because he was only 17 at the time of the murder. His last legal residence was the Tonto Natural Bridge region. Following the 1877 massacre of several Chinese workers who were building a railroad through northern Arizona, legislation passed that year barred all non-whites from entering the territory. Because of its isolated location, the Tonto Natural Bridge has been a tourist attraction since before European settlement. “Natural” refers to the fact that no artificial structures support the bridge; it is simply a pile of stone held up by the surrounding native rocks. Visitors could enter the structure and explore its many caves and crevices. During the 1870s and 1880s, railroads arrived in the area to serve the mining economy, and tourism became a major industry. Tourists flocked to the new rail stations to enjoy the scenery and get a look at the famous bridge. By 1920, more than 100 trains per day stopped in the area, carrying nearly 200,000 passengers each way. At least three movies were shot in the area: Angel and the Badman (1946), Broken Arrow (1950), and Drum Beat (1954).
A scenic railway known as the Cascade Railroad operated between 1912 and 1956, hauled by steam locomotives along a 3ft (0.91m) narrow gauge track laid atop the right-of-way of the former Prescott, Phoenix & Tucson Railway. This railway connected the east terminus of the Superstition Freeway with Sky Harbor International Airport, where the Cascade’s passenger station still stands today. The railway also carried freight traffic from local farms and ranches to the port of Los Angeles. Steam engine No. 2872, nicknamed Old Iron Baron, was built by the Baldwin Locomotive Works and delivered to the Cascade Railroad in May 1942. She remained in service until December 1955, when she suffered a boiler explosion during a cold start and burned beyond repair. Her sister ship, was similarly destroyed by fire in 1960. Although both ships have been scrapped, their hulls lie in good condition near the natural bridge, serving as landmarks and providing a habitat for wildlife. On January 14, 2006, severe thunderstorms swept through the area, causing damage to the landscape and breaking windows throughout the region.
Due to the extensive amount of rain, the Tonto Natural Bridge was severely damaged, closing the park indefinitely. After much debate, the state decided to reopen the park in summer 2007, offering guided tours once again. The main feature of the park, the Tonto Natural Bridge, reopened to the public on July 23, 2007, though access was restricted to those with tickets reserved on a tour boat departing from the Pearl Preserve Marina. As of February 2012, there are no plans to open the park to the general public. The park can be accessed by train on the Prescott, Phoenix & Tucson Railway historic line from the east terminus of the Superstition Freeway at SR 87. There are four tracks present, plus a fifth track laid down express, which bypasses regular service to the southbound direction. Trains stop in both directions, roughly every half mile. The western terminus of the line is the Holbrook depot, from which the majority of trains operate into the park. The first part of the journey is level, then gradually climbs a 4% grade uphill to the trestle over the river.
Beyond the trestle, the line traverses Baldy Mountain and descends back to the valley floor. From here, it is mostly flat, crossing Farmington Creek just past the old log cabin. Past Farmington Creek lies the steepest section of the route, climbing 7% grades twice, the second time reaching a maximum elevation of 640 feet (200m). Just past the second climb comes a 2% downgrade, followed by a third climb, this time 8%, before descending 6% to the finish line. Most trips begin at the East End platform outside the park visitor center and make a loop of the lower portion of the route before returning to the beginning. The round trip distance is approximately five miles (8.0km). Other portions of the Prescott, Phoenix & Tucson Railway branch off from the main line include a shuttle service across the river from the East End platform to the South Entrance/Parking lot, and a separate trailhead at Cottonwood Campground, served by a single daily train. This article contains content in the public domain published by the Arizona Department of Transportation.