National Weather Service Baltimore/Washington

On January 29, 2011, Bethany Anne Decker (née Littlejohn; born May 13, 1989) left her husband's parents' home in Maryland and returned to her apartment in Ashburn, Virginia. Her boyfriend, Ronald Roldan, says he saw her there later that day. She has not been seen since. While Decker did not show up at her job or classes she took at nearby George Mason University, her absence was not noted for another three weeks, since messages to her friends purportedly from her continued to be posted on her Facebook account. After her family noted her absence otherwise, they found her car parked near her apartment. Apart from the Facebook posts, there had been no other evidence she had done anything since the day she was last seen. They reported her missing to Loudoun County Sheriff's Office. Decker was five months pregnant at the time of her disappearance. Extensive searches have found no trace of her or the child she might have given birth to. Roldan, who had a criminal record prior to the disappearance, was arrested in North Carolina in 2015 and charged with the attempted murder of another girlfriend after he shot her during an incident in 2014; he has not said anything about the Decker case. After she recovered, the victim claimed on the Dr. Phil show that he had made statements to her that might implicate him in Decker's disappearance. Roldan pled guilty to two lesser charges in 2016; after he served his sentence, he was expected to be deported to his native Bolivia. Instead, he was charged with Decker's abduction upon his release in 2020 and returned to Loudoun County. The incident has been the subject of a segment of the Investigation Discovery channel series Disappeared.

Horsepen Creek is one of the streams that flow into the Potomac River and then into the Chesapeake Bay. Horsepen Creek lies in Fairfax County, Virginia, a major county in Northern Virginia on the U.S. East Coast.

Loudoun Valley Estates is a census-designated place (CDP) in Loudoun County, Virginia, United States. The population as of the 2010 United States Census was 3,656. It is a Toll Brothers community located near the planned Ashburn Metro station complex and Moorefield Station town center in the southern part of Ashburn, Virginia. Loudoun Valley Estates is governed by a homeowners' association.It was formerly part of the county planning commission's Urban Policy Area but has been removed. The community is served by the Loudoun County Parkway.

Moorefield is a census-designated place (CDP) in Loudoun County, Virginia, United States. As of the 2010 census, the CDP was named Moorefield Station, and the population was 77. As of 2019, the estimated population was 1,976. Moorefield is a mixed-use development currently in progress, located at the Ashburn station currently under construction at the planned terminus of the Metrorail Silver Line.

Ashburn is a planned Washington Metro station in Loudoun County, Virginia, United States, on the Silver Line. Originally planned to begin operation in 2018, the station is now expected to open in July 2022. Ashburn will be the western terminus of the line; the current western terminus is Wiehle–Reston East station, which opened with phase one of the Silver Line in July 2014.In April 2015, the Washington Metropolitan Area Transit Authority approved the Loudoun County Board of Supervisors' name for the stop.Ashburn station is located at the median of the Dulles Greenway (SR 267) east of Old Ryan Road (SR 772). It will be the furthest station from the Washington city center, and the closest to West Virginia, being only 26.5 miles (42.6 km) by road from Keyes Gap.

Loudoun Gateway is a planned Washington Metro station in Loudoun County, Virginia on the Silver Line. It will be located at SR 606 (Old Ox Road) and the ramps to SR 267. Originally planned to begin operations in 2018, the station is now is now expected to open in July 2022. In April 2015, the Washington Metropolitan Area Transit Authority approved the Loudoun County Board of Supervisors' name for the stop.

Ryan is an unincorporated community in Loudoun County, Virginia, United States. The community was once at the corner of Shellhorn, Ryan, and Waxpool roads. It is now a part of the Ashburn communities.

American Airlines Flight 444 was a scheduled American Airlines flight from Chicago to Washington, D.C.'s National Airport. On November 15, 1979, the Boeing 727 serving the flight was attacked by "the Unabomber", Ted Kaczynski, who sent the bomb in the mail and set it to detonate at a certain altitude. The bomb partially denotated in the cargo hold and caused "a sucking explosion and a loss of pressure," which was then followed by large quantities of smoke filling the passenger cabin, forcing the pilots to make an emergency landing at Dulles International Airport. Twelve passengers had to be treated afterward for smoke inhalation.

Dulles International Airport is a planned Washington Metro station at Washington Dulles International Airport in Loudoun County, Virginia, U.S., on the Silver Line. Originally planned to be operational by 2018, the station is now expected to open in July 2022. The station was originally planned to be underground, but was built as an above-ground station next to daily parking garage one.

Washington Dulles International Airport (IATA: IAD, ICAO: KIAD, FAA LID: IAD), typically referred to as Dulles International Airport, Dulles Airport, Washington Dulles or simply Dulles ( DUL-iss), is an international airport in the Eastern United States, located in Loudoun County and Fairfax County in Virginia, 26 miles (42 km) west of Downtown Washington, D.C. Opened in 1962, it is named after John Foster Dulles (1888–1959), the 52nd U.S. Secretary of State who served under President Dwight D. Eisenhower. The Dulles main terminal is a well-known landmark designed by Eero Saarinen, who also designed the famous TWA terminal (now the TWA hotel) at New York's JFK airport. Operated by the Metropolitan Washington Airports Authority, Washington Dulles Airport occupies 13,000 acres (20.3 sq mi; 52.6 km2) straddling the Loudoun–Fairfax line. Most of the airport is in the unincorporated community of Dulles in Loudoun County, with a small portion in the unincorporated community of Chantilly in Fairfax County. Dulles is one of the three major airports in the larger Baltimore–Washington metropolitan area, the others being Reagan National Airport and Baltimore/Washington International Airport, and by land size and amount of facilities is the largest of the three. Dulles is considered the region's international air hub, with dozens of nonstop international flights. Dulles has the most international passenger traffic of any airport in the Mid-Atlantic outside the New York metropolitan area, including approximately 90% of the international passenger traffic in the Baltimore–Washington region. It had more than 20 million passenger enplanements every year from 2004 to 2019, with 24 million enplanements in 2019. On a typical day, more than 60,000 passengers pass through Dulles to and from more than 125 destinations around the world.Increased domestic travel from Reagan National Airport has eroded some of Dulles's domestic routes. Dulles overtook Reagan in total enplanements in 2019. However, in 2018, Dulles Airport surpassed Ronald Reagan Washington National Airport (DCA) in yearly passenger boardings after having fewer passengers since 2015. Furthermore, it still ranks behind Baltimore/Washington International Thurgood Marshall Airport (BWI) in total annual passenger boardings.Dulles is a hub for United Airlines and is frequently used by airlines which United has codeshare agreements with, mostly composed of Star Alliance members like Turkish Airlines and Lufthansa.

The Dulles International Airport Main Terminal is located in Loudoun and Fairfax counties in Dulles, Virginia, United States. The original structure, 600 feet (180 m) long and 150 feet (46 m) wide, was designed by Eero Saarinen and completed in 1962 as the first terminal at Dulles International Airport. Annexes to the west and east were completed in 1996 as part of a renovation designed by Skidmore, Owings & Merrill, bringing its total length to 1,240 feet (380 m). The terminal is operated by the Metropolitan Washington Airports Authority, which operates Dulles Airport as a whole. The terminal's design is a suspended structure with roof panels of precast concrete suspended between cables which span the width of the building. The Main Terminal's design includes parallel slanted colonnades on the terminal's north and south facades, interspersed with glass walls. The landside facade to the north is taller than the airside facade to the south; a concave roof supported by cables connects the two facades, descending at the center. A concourse and control tower extend south toward the airport's apron. The interior was originally divided into two levels: an upper story for departing passengers and a lower story for arriving passengers. Saarinen's original design included mobile lounges that ferried passengers directly to planes, reducing the need for long walks or taxiing while increasing the airport's operational flexibility. The modern terminal includes four Z gates, where aircraft could unload passengers directly. In addition, two basements contain security screening facilities and an AeroTrain people-mover station. The 1950 Washington Airport Act provided funding for Dulles Airport, land for which was acquired in January 1958. Saarinen was selected that May to design the terminal, construction of which began in early 1960. After several delays, the terminal was dedicated on November 17, 1962, along with the rest of the airport. Initially, Dulles Airport saw lower-than-expected usage, but increased patronage prompted the airport's original operator, the Federal Aviation Administration (FAA), to contemplate an expansion in the early 1970s. Hellmuth, Obata & Kassabaum (HOK) built two small annexes to the south in 1978, and further expansions and additional terminals were contemplated in the 1980s following increases in patronage. SOM designed annexes to the west and east, which began construction in October 1993 and were dedicated on September 6, 1996. Additional expansions took place in the 2000s, including the Z gates and the basements. The structure was widely acclaimed when it was completed, particularly regarding its shape, and Saarinen reportedly considered it his best work. The terminal has also received numerous awards, including the American Institute of Architects' Twenty-five Year Award, and other terminal buildings have been compared with it. Though the Main Terminal was nominated for inclusion on the National Register of Historic Places in 1978, it was never added due to objections from the FAA.

Dulles () is an unincorporated area in Loudoun County, Virginia, United States, and is part of the Washington metropolitan area. The headquarters of Northrop Grumman Innovation Systems and ODIN Technologies, as well as the former headquarters of MCI Inc. and AOL are located in Dulles. The National Weather Service Baltimore/Washington forecast office and the National Weather Service's Sterling Field Support Center are also both in Dulles.