The Grand Canyon is a steep canyon carved by the Colorado River in Arizona, United States. It stretches 277 miles in length, reaches a width of up to 18 miles, and plunges to depths exceeding one mile. It is one of the most famous and visited natural landmarks in the United States.
Powell's directorship of the U.S. Bureau of Ethnology of the Smithsonian Institution ended in 1902.
In 1903, U.S. President Theodore Roosevelt, an avid outdoorsman and conservationist, visited the Grand Canyon.
In 1903, the National Weather Service established a cooperative station on the South Rim of the Grand Canyon.
On November 28, 1906, Theodore Roosevelt established the Grand Canyon Game Preserve, reducing livestock grazing and eradicating predators.
On January 11, 1908, adjacent national forest lands were added and the Grand Canyon Game Preserve was redesignated a U.S. National Monument.
In 1908, the Grand Canyon was officially designated as a National Monument.
From 1916 to 2014, naturalized streamflow in the Upper Colorado River Basin decreased by 16.5%.
On January 1, 1919, the record low temperature of −20 °F (−29 °C) was recorded on the South Rim of the Grand Canyon.
On February 26, 1919, the Grand Canyon National Park was established as the 17th U.S. National Park by an Act of Congress signed by President Woodrow Wilson.
In 1919, the Grand Canyon was officially designated as a National Park.
In 1926, the first dual distribution water system in the United States was built on the South Rim, treating and reclaiming wastewater for nonpotable reuse.
Groundwater at sites across the Grand Canyon region contain a fraction of modern water (post-1950), indicating a mix of recent and older water sources.
On the morning of June 30, 1956, a TWA Lockheed Super Constellation and a United Airlines Douglas DC-7 collided above the Grand Canyon.
In 1956, the Grand Canyon was the site of the deadliest commercial aviation disaster in history at the time.
In 1963, the construction of the Glen Canyon Dam significantly altered the Grand Canyon's ecosystem by reducing average flood levels.
On June 26, 1974, the record high temperature of 105 °F (41 °C) was recorded on the South Rim of the Grand Canyon.
On September 1, 1981, a study began examining samples of groundwater from 180 spring sites and 26 wells in the Grand Canyon region to assess the presence of uranium.
In 1984, the last aerial video footage from below the rim of the Grand Canyon was filmed.
On February 1, 1985, the record low temperature of −20 °F (−29 °C) was recorded on the South Rim of the Grand Canyon.
On December 23, 1990, the record low temperature of −20 °F (−29 °C) was recorded on the South Rim of the Grand Canyon.
In 1990, amendments to the Clean Air Act established the Grand Canyon Visibility Transport Commission (GCVTC).
Activity at the Pinyon Plain Mine (formerly Canyon Uranium Mine) had ceased in 1992, ten years prior to the moratorium on new development in 2012.
In 1996, Federal officials started releasing floods in the Grand Canyon in hopes of restoring its ecosystem.
In 1996, the GCVTC released its final report and initiated the Western Regional Air Partnership (WRAP).
From 1997 through 1999, scrubbers were added to the Navajo Generating Station's three units to reduce SO2 emissions by 90%.
As of 1999, the Grand Canyon area had some of the cleanest air in the United States.
From 1997 through 1999, scrubbers were added to the Navajo Generating Station's three units to reduce SO2 emissions by 90%.
In 1999, the Regional Haze Rule was established with the goal of restoring visibility in national parks and wilderness areas to natural background levels by 2064.
An analysis of fatalities from 1869 to 2001 revealed causes such as falls, environmental factors, flash floods, drownings, and plane crashes.
In September 2003, a survey of visitors to the Grand Canyon was conducted to gather information about the demographics of park attendees.
Between 2003 and 2011, 2,215 mining claims had been requested adjacent to the canyon.
Through August 2004, a survey of visitors to the Grand Canyon was conducted to gather information about the demographics of park attendees.
In 2004, Federal officials released floods in the Grand Canyon in hopes of restoring its ecosystem.
In 2005, the Mohave Generating Station was shut down, completely eliminating its emissions.
In 2007, the glass-bottomed Grand Canyon Skywalk was opened on the Hualapai reservation, attracting thousands of visitors annually.
In 2008, Federal officials released floods in the Grand Canyon in hopes of restoring its ecosystem.
In 2008, Rebecca Flowers reported apatite (U-Th)/He thermochronometry results suggesting that parts of the Grand Canyon had reached a depth near to the modern depth around 20 million years ago.
In 2008, Victor Polyak's study, published in Science, dated the origins of caves near the Grand Canyon to approximately 17 million years ago using uranium-lead dating of calcite deposits.
In the National Park Service's "Climate Action Plan," goals were set to reduce greenhouse gases 30 percent below 2008 levels by 2020.
From 2009–2011, low-NOx SOFA burners were installed at the Navajo Generating Station, reducing emissions of NOx by 40%.
In 2009, U.S. Interior Secretary Ken Salazar published a Notice of Intent to suspend approvals for new uranium mining in the Grand Canyon area.
Between 2003 and 2011, 2,215 mining claims had been requested adjacent to the canyon.
From 2009–2011, low-NOx SOFA burners were installed at the Navajo Generating Station, reducing emissions of NOx by 40%.
In 2012, Interior Secretary Ken Salazar established a 20-year moratorium withdrawing 1 million acres from uranium and hardrock mining permitting.
In 2012, the federal government implemented a moratorium.
In 2012, the moratorium on new development happened.
In a study published in Science in 2012, Rebecca Flowers suggested that the western part of the Grand Canyon could be as old as 70 million years.
In November 2014, the moratorium was appealed as National Mining Association v. Jewell (No. 14-17350).
From 1916 to 2014, naturalized streamflow in the Upper Colorado River Basin decreased by 16.5%.
In 2014, plans were announced for the Grand Canyon Escalade, a multimedia complex featuring shops, an IMAX theater, hotels, and a gondola for canyon access.
By 2015, approximately 770 deaths had occurred in the Grand Canyon between the mid-1800s and 2015.
In 2016, skydiving at the Grand Canyon became possible with the opening of the first Grand Canyon Skydiving operation at the Grand Canyon National Park Airport, on the South Rim.
On October 31, 2017, the Navajo Nation Council voted against the Grand Canyon Escalade project.
In 2017, the 9th Circuit Court of Appeals upheld the moratorium, affirming the Secretary of the Interior's withdrawal authority.
In 2018, the Department of Interior began experimenting with "adaptive management" of the Glen Canyon Dam, using a High-Flow Experiment (HFE) water release.
As of 2019, plans to replace the aging 16-mile aluminum Transcanyon Pipeline were proposed.
In 2019, the Navajo Generating Station shut down completely.
On October 3, 2020, former Major League Baseball player Charlie Haeger was found dead from a self-inflicted gunshot wound on a canyon trail.
A study examining samples of groundwater from 180 spring sites and 26 wells in the Grand Canyon region ended on October 7, 2020.
In the National Park Service's "Climate Action Plan," goals were set to reduce greenhouse gases 30 percent below 2008 levels by 2020.
On February 22, 2022, the 9th U.S. Circuit Court of Appeals rejected arguments in No. 20-16401, concluding that the Forest Service had not acted arbitrarily in its decision regarding the Pinyon Plain Mine.
As of 2022, extreme drought caused water levels in Lake Powell to drop, delaying a planned water release to ensure the Glen Canyon Dam can generate hydropower.
On August 8, 2023, it was announced that U.S. President Joe Biden will designate Baaj Nwaavjo I’tah Kukveni – Ancestral Footprints of the Grand Canyon National Monument.
In 1999, the Regional Haze Rule established a goal of restoring visibility in national parks and wilderness areas to natural background levels by 2064.