The Rio Grande Trivia
0Loading crowd target
0Loading crowd target
6correct to beat the crowd
58 free The Rio Grande trivia questions with answers — geography quiz, new questions added Oct 2026.
Rio Grande trivia covers North America's fourth-longest river from Canby Mountain in Colorado to the sandbar-choked delta on the Gulf of Mexico. The quiz starts with the basics: what Mexicans call it, how long it is, where it rises, which four Mexican states it borders, where the border stretch begins, and how little of its water now reaches the sea. Then geography: the Rio Conchos that refills the 'Forgotten River', the Pecos and Devils rivers, the Taos gorge and its high bridge, the Rio Grande rift, Albuquerque's altitude and the ancient lakes the river drained. The history section covers Coronado and Oñate, the Nueces strip and the Republic of Texas, Guadalupe Hidalgo, 200 steamboats to Rio Grande City, the Confederacy's port of Bagdad, the swing bridge at Brownsville, the Chamizal dispute from Cordova Island to the 1964 treaty, the Díaz–Taft summit, the 1938 compact, the 1944 treaty and the IBWC. Then dams and drought: Elephant Butte and its elephant, Falcon Dam's two presidents, a reservoir at 6.4% and a river dry in Albuquerque. It closes with Big Bend's three canyons and Chisos Mountains, Pueblo names, the silvery minnow, the San Juan–Chama tunnel and John Ford's Rio Grande. Every answer was checked against Wikipedia's articles on the Rio Grande, the Chamizal dispute, Big Bend National Park and the river's dams and bridge, with the supporting sentence attached to each question. Easy questions suit any geography fan; the expert tier reaches Lake Palomas and 889 cubic feet per second.
30 of 58 questions with answers and explanations. Play the quiz
Q 01What is the Rio Grande called in Mexico?
Río Bravo
Río Bravo. Bravo means wild or turbulent, and Mexico kept that old Spanish name for the lower river while American settlers in South Texas made Rio Grande the usual name on their side.
Q 02The Civil War's last land battle came on the Rio Grande over a month after whose surrender?
Robert E. Lee
Robert E. Lee. Both commanders at Palmito Ranch, near Brownsville, knew the war in the east was over when they fought on 13 May 1865; the Confederates won, then surrendered within weeks.
Q 03Which of these rivers is longer than the Rio Grande?
The Yukon
The Yukon. It runs about 1,980 miles against roughly 1,900 for the Rio Grande, whose length shifts as its course changes; depending on how it is measured, it ranks fourth or fifth in North America.
Q 04In which US state does the Rio Grande rise?
Colorado
Colorado. The river starts as a clear, snow-fed stream about 12,000 feet up near the Continental Divide, a cold mountain birth for a river best known as a desert border.
Q 05Into which body of water does the Rio Grande empty?
The Gulf of Mexico
The Gulf of Mexico. Dams and irrigation in both countries take so much water on the way that only a fraction of the river's natural flow ever arrives.
Q 06Texas's Lower Rio Grande Valley, irrigated by the river, is best known for which fruit, sold as Ruby Red?
Grapefruit
Grapefruit. The Ruby Red began as a freak of nature, a branch bearing red fruit on a pink-grapefruit tree in the Valley around 1929, and Texas later named red grapefruit its state fruit.
Q 07Which four Mexican states border the Rio Grande?
Chihuahua, Coahuila, Nuevo León and Tamaulipas
Chihuahua, Coahuila, Nuevo León and Tamaulipas. All four face a single American state, Texas, across the water, and Nuevo León reaches the river only through one narrow strip of land.
Q 08Which pair of twin cities marks the point where the Rio Grande starts to form the US–Mexico border?
El Paso and Ciudad Juárez
El Paso and Ciudad Juárez. The Mexican city was itself called El Paso del Norte until 1888, when it was renamed for Benito Juárez, who had run his government from the town while fighting the French.
Q 09Which Mexican tributary joins the Rio Grande near Ojinaga and restores its flow after it nearly dries near Presidio?
Rio Conchos
Rio Conchos. It is the Rio Grande's biggest tributary by flow, so from here on the river along the Texas border is carrying largely water that fell on Mexico's Sierra Madre.
Q 10Which two US tributaries join the Rio Grande from the north near Amistad Reservoir?
The Pecos and Devils rivers
The Pecos and Devils rivers. Both now end in Lake Amistad, a reservoir the United States and Mexico built together on the border and finished in 1969.
Q 11The Rio Grande Gorge, likely cut when ancient Lake Alamosa spilled over, lies near which New Mexico town?
Taos
Taos. The overflow, hundreds of thousands of years ago, also drained the lake for good and joined the high San Luis Valley upstream to the river.
Q 12Which 1994 film stages a wedding on New Mexico's Rio Grande Gorge Bridge?
Natural Born Killers
Natural Born Killers. The bridge is one of the highest in the United States, though nobody agrees quite how high: published figures run from about 565 to 650 feet above the river.
Q 13Which secret wartime laboratory built the first atomic bombs on a plateau above New Mexico's Rio Grande?
Los Alamos
Q 21Which 1848 agreement defined the US–Mexico border as the middle of the Rio Grande's deepest channel?
The Treaty of Guadalupe Hidalgo
The Treaty of Guadalupe Hidalgo. Because the river kept shifting its bed, a border tied to its channel moved too, and the two countries spent decades arguing over land the water had carried across.
Q 22At Los Ebanos, Texas, people still cross the Rio Grande to Mexico on the river's last what?
Hand-pulled ferry
Hand-pulled ferry. Since 1950 a crew has hauled the barge across by rope, its cable anchored to one of the ebony trees that gave Los Ebanos its name.
Q 23What was Cordova Island, created when an 1899 channel cut across a Rio Grande bend?
Los Alamos. In late 1942 the Army settled on an isolated boys' ranch school on the mesa, a site pushed by Robert Oppenheimer, who knew the country from his youth.
Q 14What did the Rio Grande do at its mouth in 2001?
Failed to reach the sea
Failed to reach the sea. Farms and cities had pumped out so much that the last trickle died in the sand about a hundred yards short of the surf, and locals joked that the sandbar was the newest bridge to Mexico.
Q 15Which cattle baron made his first fortune as a Rio Grande steamboat captain before founding a huge South Texas ranch?
Richard King
Richard King. A New York runaway who stowed away on a ship as a boy and was piloting steamboats at sixteen, he came to the border to carry army supplies, built a near-monopoly on the river trade and went on to found the King Ranch.
Q 16Which boomtown at the Rio Grande's mouth let the Confederacy trade with Europe despite the Union blockade?
Bagdad, Tamaulipas
Bagdad, Tamaulipas. It stood on neutral Mexican soil, so the Union navy could not blockade it, and supplies landed there were hauled 25 miles upriver and slipped across into Texas.
Q 17The Brownsville & Matamoros International Bridge, dating from 1910, is what type of bridge?
A swing span
Its swing mechanism has not been used since the last big steamboats vanished in the early 1900s.
Q 18Which Spanish expedition first reached the Tiwa pueblos along the Rio Grande in 1540?
Coronado's
Coronado's. His army wintered among the Tiwa in 1540–41, seized their food and clothing against the cold, and set off the Tiguex War, which left the pueblos along the river destroyed.
Q 19Who founded the Spanish colony of Santa Fe de Nuevo Méjico in 1598, where the Rio Grande meets the Rio Chama?
Juan de Oñate
Juan de Oñate. He ruled the colony so harshly that Spain later tried him for excessive force against Acoma Pueblo, fined him and banished him from New Mexico for life.
Q 20Which river did Mexico claim as its border with the Republic of Texas, rather than the Rio Grande?
The Nueces
The Nueces. When US troops marched from Corpus Christi, at its mouth, to the Rio Grande in 1846, Mexico treated the move as an act of war, and the clash that followed gave President Polk his case for war.
A piece of Mexico inside US territory
A piece of Mexico inside US territory. Almost surrounded by American soil, it became a notorious haven for smugglers during Prohibition, when a saloon called the Hole in the Wall traded a few yards from the line.
Q 24After the 1960s Chamizal settlement, what was built to stop the Rio Grande shifting the border?
Concrete riverbed
Concrete riverbed. The two countries split the cost of lining the river's new course, and the land handed back to Mexico became a public park.
Q 25Which two presidents met at El Paso in 1909 for the first US–Mexico presidential summit?
Porfirio Díaz and William Howard Taft
Porfirio Díaz and William Howard Taft. On the day they met, guards seized a man hiding a palm pistol only a few feet from the two presidents' route, and the summit went ahead.
Q 26The 1938 agreement dividing the Rio Grande's US water among three states is called the Rio Grande what?
Compact
Compact. Under the Rio Grande Compact the states keep score in water debits and credits measured at gauging stations, and their quarrels over the sums have reached the US Supreme Court more than once.
Q 27Which US–Mexico agency, founded in 1889, straightened 155 winding miles of the Rio Grande into 86?
The International Boundary and Water Commission
The International Boundary and Water Commission. It was set up just to settle where the border lay whenever the river moved, and in the 1930s it cut out the bends so the boundary would stay put.
Q 28Truth or Consequences, the New Mexico town beside Elephant Butte Dam, renamed itself in 1950 after what?
A radio quiz show
A radio quiz show. Host Ralph Edwards promised to broadcast from the first town to take his show's name; Hot Springs voted yes within weeks, and Edwards came back for its fiesta every May for 50 years.
Q 29Elephant Butte gets its name from what?
A volcanic plug shaped like the animal, lying down
A volcanic plug shaped like the animal, lying down. The hard core of an eroded volcano, it turned into an island when the reservoir filled behind the dam, which engineers first called Engle Dam.
Q 30New Mexico's Hatch Valley, irrigated by the Rio Grande, is world-famous for which crop?
Chile peppers
Chile peppers. The same pods are sold green when picked early and red once they ripen, which is how New Mexico came to have an official state question: 'Red or green?'