Question: Which is longer, the Madera Canal or the All-American Canal?
Context: The Delta–Mendota Canal is a 117 mi aqueduct in central California, United States.  It is part of the Central Valley Project and its purpose is to replace water in the San Joaquin River that is diverted into Madera Canal and Friant-Kern Canal at Friant Dam.  Average annual throughput is 1993000 acre feet . Brock Reservoir is a man-made reservoir located near Gordons Well, California.  When a water request from Lake Mead is made, it takes time to travel the canal system to its destination.  If the request is changed or canceled before it reaches its destination, the water is diverted to Brock Reservoir for storage.  It has a small maximum volume of only 8000 acre ft , but is expected to be filled and emptied many times each year.  It holds water from the All-American Canal until it can be used for nearby agriculture. The Madera Canal is a 35.9 mi aqueduct in the U.S. state of California.  It is part of the Central Valley Project managed by the United States Bureau of Reclamation to convey water north to augment irrigation capacity in Madera County, California.  It was also the subject of the United States Supreme Court's decision in Central Green Co. v. United States. The All-American Canal Bridge is a bridge that carries Interstate 8 over the All-American Canal, a canal that supplies water from the Colorado River to the agricultural areas of the Imperial Valley. The All-American Canal is an 80-mile (130 km) long aqueduct, located in southeastern California.  It conveys water from the Colorado River into the Imperial Valley and to nine cities.  It is the Imperial Valley's only water source, and replaced the Alamo Canal, which was located mostly in Mexico.  The Imperial Dam, about 30 miles (48 km) northeast of Yuma, Arizona on the Colorado River, diverts water into the All-American Canal, which runs to just west of Calexico, California before its last branch heads mostly north into the Imperial Valley.  Five smaller canals branching off the All American Canal move water into the Imperial Valley.  These canal systems irrigate up to 630,000 acres (250,000 ha) of crop land and have made possible a greatly increased crop yield in this area, originally one of the driest on earth.  It is the largest irrigation canal in the world, carrying a maximum of 26,155 cubic feet per second (740.6 m/s).  Agricultural runoff from the All American Canal drains into the Salton Sea. Harriet Williams Russell Strong (July 23, 1844 – September 6, 1926) was an American social activist, inventor, conservationist, and leading figure of the early woman's movement.  She is a member of the National Women's Hall of Fame and the National Inventors Hall of Fame.  Her pioneering innovations in water storage and flood control enabled the construction of the Hoover dam and the All-American Canal. The Coachella Canal is a 122 mi aqueduct that conveys Colorado River water for irrigation northwest from the All-American Canal to the Coachella Valley north of the Salton Sea in Riverside County, California. Obvodny Canal (Russian: Обводный канал , lit.  Bypass Canal) is the longest canal in Saint Petersburg, Russia, which in the 19th century served as the southern limit of the city.  It is 8 km long and flows from the Neva River near Alexander Nevsky Lavra to the Yekaterinhofka not far from the sea port.  The canal was dug in 1769–80 and 1805–33.  By the late 19th century, after to the Industrial Revolution, it had effectively become a sewer collecting wastewater of adjacent industrial enterprises.  Eventually the canal became shallow and no longer navigable.  The banks of the canal are lined with granite. The Imperial Diversion Dam (National ID # CA10159) is a concrete slab and buttress, ogee weir structure across the California/Arizona border, 18 mi northeast of Yuma.  Completed in 1938, the dam retains the waters of the Colorado River into the Imperial Reservoir before desilting and diversion into the All-American Canal, the Gila River, and the Yuma Project aqueduct.  Between 1932 and 1940, the Imperial Irrigation District (IID) relied on the Inter-California Canal and the Imperial Canal and Alamo River. State Route 186 (SR 186) is a route that connects Interstate 8 (I-8) with the U.S.–Mexico border near the Colorado River.  Its southern terminus is near Los Algodones, Baja California, and its northern terminus is near Winterhaven, California in the location of Araz Junction.  The route is only 2.070 mi long, heading along the length of the Alamo Canal and the All-American Canal within the boundaries of the Fort Yuma-Quechan Reservation.  The route was assigned in 1972 in Imperial County, and the interchange with I-8 was constructed a year later.
Answer: the All-American Canal