nonstop from Chicago O'Hare, Denver, Cedar Rapids and Peoria, IL. The original Frontier Airlines ceased operations in 1986; successor Continental Airlines flew 737s and DC-9s to Denver. United mainline jet service was eventually replaced by flights operated by its United Express partners who now fly 50 seat regional jets from LNK. In 2005, Northwest Airlines flew to Memphis but dropped the route within nine months. In early 2006, Allegiant Air began air service to Las Vegas but after two years, announced that it was transferring service to Grand Island, NE. In May 2014 Delta Air Lines announced a non-stop flight to Atlanta would start September 8, resuming a service it briefly ran in 2009. In 2011 Delta resumed the Memphis service, but only over the summer. $750,000 in federal spending was used to guarantee revenue for Delta. Today part of Lincoln Airport is home to the Nebraska Air National Guard's 155th Air Refueling Wing (155 ARW), an Air Mobility Command (AMC)-gained Air National Guard unit flying the KC-135R Stratotanker. Several Nebraska Army National Guard units are collocated at the installation, just east of Runway 36 alongside Taxiway Delta. The Air National Guard's tarmac is closed to general aviation and is guarded by Air Force Security Forces 24 hours a day. Facilities Lincoln Airport covers at an elevation of . It has three asphalt/concrete runways: 18/36 is 12,901 by 200 feet (3,932 x 61 m); 14/32 is 8,649 by 150 feet (2,636 x 46 m); and 17/35 is 5,800 by 100 feet (1,768 x 30 m). In the year ending March 31, 2016 the airport had 62,770 aircraft operations, average 172 per day: approximately 59% general aviation, 21% military, 13% airline and 7% air taxi. 199 aircraft were then based at this airport: approximately 53% single-engine, approximately 25% multi-engine, 12% military, 7% jet and 3% helicopter. Air National Guard The current Lincoln Air National Guard Base is home to the Nebraska Air National Guard's 155th Air Refueling Wing (155 ARW), an Air Mobility Command (AMC)-gained Air National Guard unit flying the KC-135R Stratotanker. The 155 ARW is the nation's second oldest Air National Guard unit, being offered federal recognition on 26 July 1946 as the 173rd Fighter Squadron. It operates from a new facility built on the southeast side of the main runway. Several Nebraska Army National Guard units are also collocated at the installation, located just east of Runway 36,