Denver has traditionally been home to one of the busier airports in the United States because its midcontinent location was ideal for an airline hub. Several airlines, notably United Airlines and Continental Airlines, had hubs at the former Stapleton International Airport, helping make it the sixth-busiest airport in the country by the 1960s. However, Stapleton had little room to add more flights and its runways were too close together, which led to long delays and nationwide travel disruptions in bad weather. From 1980 to 1983, the Denver Regional Council of Governments investigated areas for a new area airport north and east of Denver. Meanwhile, in 1983, Federico Peña was elected mayor of Denver, campaigning on a plan to expand Stapleton onto Rocky Mountain Arsenal lands. The plan had broad support, but leaders in nearby Adams County threatened to sue over noise concerns. Eventually Peña struck a deal: Adams County leaders would rally citizens to back a plan for Denver to annex 54 square miles (140 km2) of the county to build an airport away from established neighborhoods. In 1988, Adams County voters approved the annexation. The proposal was met with some skepticism because of its location: 24 miles (39 km) from the heart of the city. But seeing the importance of a Denver air hub to the national transportation system, the federal government put $500 million (equivalent to $1.1 billion as of 2024) toward the new airport. The rest of the cost would be financed by bonds, to be repaid with fees on airlines. Ground was broken in September 1989. Two years later, Mayor Wellington Webb inherited the megaproject, which at that time was scheduled to open on October 29, 1993. At the time United was refusing to move to the new airport over the high proposed fees. The airline finally relented under the condition that the airport include an automated baggage system. Construction delays pushed opening day back, first to December 1993, then to March 1994. By September 1993, delays due to a millwright strike and other events meant opening day was pushed back again to May 1994. In April 1994, the city invited reporters to observe the first test of the new automated baggage system. Reporters were treated to scenes of clothing and other personal effects scattered beneath the system's tracks and carts that would often toss the luggage right off the system. After the embarrassing preview, the mayor cancelled the planned May opening. The baggage system continued to be a maintenance hassle and was finally terminated in September 2005, with traditional baggage handlers manually handling cargo and passenger luggage. DEN finally replaced Stapleton on February 28, 1995, 16 months behind schedule and at a cost of $4.8 billion (equivalent to $9 billion as of 2024), nearly $2 billion over budget ($3.7 billion as of 2024). The construction employed 11,000 workers. United Airlines Flight 1062 to Kansas City International Airport was the first to depart DEN and United Flight 1474 from Colorado Springs Airport was the first to arrive at the new airport. In September 2003, runway 16R/34L was added, the airport's sixth and at 16,000 ft (3.0 mi; 4.9 km), it is 4,000 ft (0.76 mi; 1.2 km) longer than the other runways. Its length, exceeded by only six other runways in the world, allows fully laden Airbus A380s and Boeing 747-8s to take off in the hot and high conditions at the airport, which is roughly 1 mi (1.6 km) above sea level. During a blizzard on March 17–19, 2003, the weight of heavy snow tore a hole in the terminal's white fabric roof, and over 2 feet (0.61 m) of snow on paved areas closed the airport and its main access road (Peña Boulevard) for almost two days, stranding several thousand people. Another blizzard on December 20–21, 2006, dumped over 20 inches (51 cm) of snow in about 24 hours. The airport was closed for more than 45 hours, stranding thousands.