The Disneyland Railroad (DRR), formerly known as the Santa Fe & Disneyland Railroad, is a 3-foot (914 mm) narrow-gauge heritage railroad and attraction in the Disneyland theme park of the Disneyland Resort in Anaheim, California, United States. Its route is 1.2 miles (1.9 km) long and encircles the majority of the park, with train stations in four different park areas. The rail line, which was constructed by WED Enterprises, operates with two steam locomotives built by WED and three historic steam locomotives originally built by Baldwin Locomotive Works. The ride takes roughly 18 minutes to complete a round trip on its mainline when three trains are running, and 20 minutes when four trains are running. Two to four trains can be in operation at any time, three on average.

The attraction was conceived by Walt Disney, who drew inspiration from the ridable miniature Carolwood Pacific Railroad built in his backyard. The Disneyland Railroad opened to the public at Disneyland's grand opening on July 17, 1955. Since that time, multiple alterations have been made to its route, including the addition of two large dioramas in the late 1950s and mid-1960s. Several changes have been made to its rolling stock, including the conversion of one of its train cars into a parlor car in the mid-1970s, and the switch from diesel oil to biodiesel to fuel its locomotives in the late 2000s.

The railroad has been consistently billed as one of Disneyland's top attractions, requiring a C ticket to ride when A, B, and C tickets were introduced in 1955, a D ticket to ride when those were introduced in 1956, and an E ticket to ride when those were introduced in 1959. The use of E tickets stood until a pay-one-price admission system was introduced in 1982. With an estimated 6.6 million passengers each year, the DRR has become one of the world's most popular steam-powered railroads.

Walt Disney, the creator of the concepts for Disneyland and its railroad, always had a strong fondness for trains. As a young boy, he wanted to become a train engineer like his father's cousin, Mike Martin, who told him stories about his experiences driving main-line trains on the Atchison, Topeka and Santa Fe Railway. As a teenager, he obtained a news butcher job on the Missouri Pacific Railway, selling various products to train passengers, including newspapers, candy, and cigars. Many years later, after co-founding the Walt Disney Company with his older brother Roy O. Disney, he started playing polo. Fractured vertebrae and other injuries led him to abandon the sport on the advice of his doctor, who recommended a calmer recreational activity. Starting in late 1947, he developed an interest in model trains after purchasing several Lionel train sets.

By 1948, Disney's interest in model trains was evolving into an interest in larger, ridable miniature trains after observing the trains and backyard railroad layouts of several hobbyists, including Disney animator Ollie Johnston. In 1949, after purchasing 5 acres (2.0 ha) of vacant land in the Holmby Hills neighborhood of Los Angeles, he started construction on a new residence for himself and his family, and on the elaborate 7+1⁄4 in (184 mm) gauge ridable miniature Carolwood Pacific Railroad behind it. The railroad featured a set of freight cars pulled by the Lilly Belle, a 1:8-scale live steam locomotive named after Disney's wife Lillian and built by the Walt Disney Studios' machine shop team led by Roger E. Broggie. The locomotive's design, chosen by Walt Disney after seeing a smaller locomotive model with the same design at the home of rail historian Gerald M. Best, was based directly on copies of the blueprints for the Central Pacific No. 173, a steam locomotive rebuilt by the Central Pacific Railroad in 1872. The Lilly Belle first ran on the Carolwood Pacific Railroad on May 7, 1950. Walt Disney's backyard railroad attracted visitors interested in riding his miniature steam train, and on weekends, when the railroad was operating, he allowed them to do so, even allowing some to become "guest engineers" and drive the train. In early 1953, after a visitor drove the Lilly Belle too fast along a curve, causing it to derail and injure a five-year-old girl, Disney, fearing the possibility of future accidents, closed down the Carolwood Pacific Railroad and placed the locomotive in storage.

Prior to the incident that closed his railroad, Disney consulted with Roger Broggie about the concept of including his ridable miniature train in a potential tour of Walt Disney Studios in Burbank, north of Downtown Los Angeles. Broggie, believing that there would be limited visitor capacity for the attraction, recommended to Disney that he make the train bigger in scale. The idea of a studio tour was eventually replaced by the idea of an amusement park named Disneyland across the street from the studio, and in one of its first design concepts at that proposed location, a miniature steam train ride was included, as well as a larger, narrow-gauge steam railroad attraction. During this time, Disney proposed that the narrow-gauge Crystal Springs & Southwestern Railroad, which the nearby Travel Town Museum in Griffith Park planned to build, be extended to run through Disneyland. Planned construction of the Ventura Freeway across land between the two sites, and rejection by the Burbank City Council of a new amusement park in their city, led Disney to look for a different location to build the park and its narrow-gauge railroad.

By 1953, 139 acres (56 ha) of orchard land in Anaheim in Orange County, southeast of Downtown Los Angeles, were chosen as the location for the planned Disneyland park, and on August 8, Walt Disney drew the triangular route for the future Disneyland Railroad (DRR) on the park's site plan. After financing for Disneyland was secured and all of the parcels of land at the Anaheim site were purchased, construction of the park and its railroad began in August 1954. In order to cut costs, a sponsorship deal was arranged with the Atchison, Topeka and Santa Fe Railway (AT&SF), and when it was finalized on March 29, 1955, the DRR was officially named Santa Fe & Disneyland Railroad, paying $50,000 per year. The DRR was known by that name until September 30, 1974, when the AT&SF's sponsorship ended due to the discontinuation of their passenger train business.

Prior to the start of construction of the DRR, in the hope of saving money by buying already-existing trains for the attraction, Disney tried to buy a set of 19 in (483 mm) gauge ridable miniature locomotives from William "Billy" Jones, but after Jones declined his offer, Disney decided that he wanted the railroad's rolling stock to be bigger and made from scratch. For this task, Disney again turned to Roger Broggie, who was confident that he and the Walt Disney Studios' machine shop team could use the design for Disney's 1:8-scale miniature Lilly Belle locomotive and enlarge it to build the DRR's locomotives. The exact size of the rolling stock for the new railroad was determined after Disney saw a set of narrow-gauge Oahu Railway and Land Company passenger cars that had recently arrived at the Travel Town Museum, whose dimensions Disney found to be favorable. The scale of the design for the DRR's passenger cars, based on the 3 ft (914 mm) narrow-gauge passenger cars at the Travel Town Museum, was nominally 5:8-scale when compared to the size of 4 ft 8+1⁄2 in (1,435 mm) standard gauge rolling stock. The same scale was also chosen for the steam locomotives planned for the DRR, and when its locomotives and passenger cars were completed and paired with its 3 ft (914 mm) narrow-gauge track, the railroad had nearly identical proportions to those of a conventional standard gauge railroad.