Meteor Crater, or Barringer Crater, is an impact crater about 37 mi (60 km) east of Flagstaff and 18 mi (29 km) west of Winslow in the desert of northern Arizona, United States. The site had several earlier names, and fragments of the meteorite are officially called the Canyon Diablo Meteorite, after the adjacent Canyon Diablo.

Meteor Crater lies at an elevation of 5,640 ft (1,719 m) above sea level. It is about 3,900 ft (1,200 m) in diameter, some 560 ft (170 m) deep, and is surrounded by a rim that rises 148 ft (45 m) above the surrounding plains. The center of the crater is filled with 690–790 ft (210–240 m) of rubble lying above crater bedrock. One of the features of the crater is its squared-off outline, believed to be caused by existing regional jointing (cracks) in the strata at the impact site.

Despite an attempt to make the crater a public landmark, the crater remains privately owned by the Barringer family to the present day through their Barringer Crater Company. The Lunar and Planetary Institute, the American Museum of Natural History, and other science institutes proclaim it to be the "best-preserved meteorite crater on Earth". It was designated a National Natural Landmark in November 1967.

The crater was created about 50,000 years ago during the Pleistocene epoch, when the local climate on the Colorado Plateau was much cooler and damper. The area was an open grassland dotted with woodlands inhabited by mammoths and giant ground sloths.

The object that excavated the crater was a nickel-iron meteorite about 160 ft (50 m) across. The speed of the impact has been a subject of some debate. Modeling initially suggested that the meteorite struck at up to 45,000 mph (20 km/s), but more recent research suggests the impact was substantially slower, at 29,000 mph (12.8 km/s). About half of the impactor's bulk is believed to have been vaporized during its descent through the atmosphere. Impact energy has been estimated at 10 megatons TNT_e. The meteorite was mostly vaporized upon impact, leaving few remains in the crater.

Since the crater's formation, the rim is thought to have lost 50–65 ft (15–20 m) of height at the rim crest as a result of natural erosion. Similarly, the basin of the crater is thought to have roughly 100 ft (30 m) of additional postimpact sedimentation from lake sediments and alluvium. Very few remaining craters are visible on Earth, since many have been erased by erosive geological processes. The relatively young age of Meteor Crater, paired with the dry Arizona climate, has allowed this crater to remain comparatively unchanged since its formation. The lack of erosion that preserved the crater's shape greatly accelerated its groundbreaking recognition as an impact crater from a natural celestial body.

Meteor Crater came to the attention of scientists after American settlers encountered it in the 19th century. The crater was given several early names, including "Coon Mountain", "Coon Butte", "Crater Mountain", "Meteor Mountain," and "Meteor Crater." Daniel M. Barringer was one of the first people to suggest that the crater was produced by a meteorite impact, with the Barringer family filing mining claims and purchasing it and its surroundings in the early 20th century. This led to the crater also being known as "Barringer Crater." Meteorites from the area are called Canyon Diablo meteorites, after Canyon Diablo, Arizona, which was the closest community to the crater in the late 19th century. The canyon also crosses the strewn field, where meteorites from the crater-forming event are found. The crater was initially assumed to have been formed by a volcanic steam explosion; evidence of geologically recent volcanic activity occurs across this part of Arizona – the southeastern edge of the San Francisco volcanic field is only about 20 mi (32 km) northwest of Meteor Crater.

In 1891, mineralogist Albert E. Foote presented the first scientific paper about the meteorites of Northern Arizona. Several years earlier, Foote had received an iron rock for analysis from a railroad executive. Foote immediately recognized the rock as a meteorite and led an expedition to search and retrieve additional meteorite samples. The team collected samples ranging from small fragments to over 600 lb (270 kg). Foote identified several minerals in the meteorites, including microscopic diamonds. His paper to the Association for the Advancement of Science provided the first geological description of Meteor Crater to a scientific community.

In November 1891, Grove Karl Gilbert, chief geologist for the U.S. Geological Survey, investigated the crater and concluded that it was the result of a volcanic steam explosion. Gilbert assumed that, if it were an impact crater, then the volume of the crater, as well as meteoritic material, should still be present in the crater's rim. Gilbert also assumed a large portion of the meteorite should be buried in the crater and that this should generate a large magnetic anomaly. Gilbert's calculations showed that the volume of the crater and the debris on the rim were roughly equivalent, which meant that the mass of the hypothetical impactor was missing. There were also no detectable magnetic anomalies; he argued that the meteorite fragments found on the rim were coincidental or placed there. Gilbert publicized his conclusions in a series of lectures. In 1892, Gilbert would be among the first scientists to propose that the Moon's craters were caused by impact rather than volcanism.

In 1903, mining engineer and businessman Daniel M. Barringer suggested that the crater had been produced by the impact of a large iron meteorite. Barringer's company, the Standard Iron Company, staked a mining claim on the land and received a land patent signed by Theodore Roosevelt for 640 acres (1 sq mi, 260 ha) around the center of the crater in 1903.

Barringer had amassed a small fortune as an investor in the successful Commonwealth Mine in Pearce, Cochise County, Arizona. He drew up ambitious plans for the metal he believed was buried under the crater's floor. He estimated from the size of the crater that the meteorite had a mass of 100 million tons. Iron ore of the type found at the crater was valued at the time at US$125/ton, so Barringer was searching for a lode he believed to be worth more than a billion 1903 dollars. "By 1928, Barringer had sunk the majority of his fortune into the crater – $500,000, or roughly $7 million in 2017 dollars."

Barringer's arguments were met with skepticism. At the time, the craters visible on the Moon were thought to be volcanic, and no impact craters were known. He persisted and sought to bolster his theory by locating the remains of the meteorite. At the time of discovery, the surrounding plains were covered with about 30 tons of large, oxidized iron meteorite fragments. This led Barringer to believe that the bulk of the impactor could still be found under the crater floor. Impact physics was poorly understood at the time, and Barringer was unaware that most of the meteorite vaporized on impact. He spent 27 years trying to locate a large deposit of meteoric iron, and drilled to a depth of 1,375 ft (419 m), but no significant deposit was ever found.

Barringer was politically well-connected. In 1906, at his request, President Roosevelt authorized the establishment of a post office unconventionally named "Meteor", located at Sunshine, a stop on the Atchison, Topeka and Santa Fe Railway, 6 miles (9.7 km) north of the crater. The Meteor post office closed on April 15, 1912, due to disuse.

In 1929, astronomer F.R. Moulton was employed by the Barringer Crater Company to investigate the physics of the impact event. Moulton concluded that the impactor likely weighed as little as 300,000 tonnes, and that the impact of such a body would have generated enough heat to vaporize the impactor instantly. Barringer died just ten days after the publication of Moulton's second report.

By this time, "the great weight of scientific opinion had swung around to the accuracy of the impact hypothesis ... Apparently an idea, too radical and new for acceptance in 1905, no matter how logical, had gradually grown respectable during the intervening 20 years."

Harvey Harlow Nininger was an American meteoriticist and educator, and he revived interest in scientific study of meteorites in the 1930s, and assembled the largest personal collection of meteorites up to that time. While based in Denver, Colorado, Nininger published the first edition of a pamphlet titled "A Comet Strikes the Earth", which described how Meteor Crater formed when an asteroid impacted the Earth. In 1942, Nininger moved his home and business from Denver to the Meteor Crater Observatory, located near the turn-off for Meteor Crater on Route 66. He christened the building the "American Meteorite Museum" and published a number of meteorite and Meteor Crater-related books from the location. He also conducted a wide range of research at the crater, discovering impactite, iron-nickel spherules related to the impact and vaporization of the asteroid, and the presence of many other features, such as half-melted slugs of meteoric iron mixed with melted target rock. Nininger's discoveries were compiled and published in a seminal work, Arizona's Meteorite Crater (1956). Nininger's extensive sampling and fieldwork in the 1930s and 40s contributed significantly to the scientific community's acceptance of the idea that Meteor Crater formed by the impact of an asteroid. Many of his discoveries were later observed at other relatively fresh impact craters, including Henbury and Monturaqui.

Nininger believed that the crater should be a national monument and, in 1948, he successfully petitioned the American Astronomical Society to pass a motion in support of nationalizing the crater by making "the unauthorized - and false - claim that the [Barringers] would be receptive to a fair purchase for the crater." By this time, mining activity at the crater had ceased, and the Barringers were in the process of planning a tourist attraction on the rim of the crater. Nininger was operating the American Meteorite Museum nearby, on Route 66, at the time. Nininger hoped that a public museum could be built on the crater's rim, and that the project might lead to the founding of a federal institute of meteorite research. Offended by Nininger's attempt to nationalize the crater, the Barringer family promptly terminated his exploration rights and ability to conduct further fieldwork at the crater. A few years later, in 1953, the Standard Iron Company was renamed the "Barringer Crater Company," and a private museum was constructed on the crater rim.