The story
The airline was reformed from the remnants of short-lived Potomac Air, which was created in late 2000 and started flying 37-seat de Havilland Canada Dash 8-200 aircraft in early 2001, based at Ronald Reagan Washington National Airport in Arlington County, Virginia near Washington D.C. Potomac ceased operations during the closure of Reagan National after the September 11 terrorist attacks; US Airways then reformed Potomac as MidAtlantic in the spring of 2002. MidAtlantic officially launched on Sunday, April 4, 2004, with service from Pittsburgh.
Some CRJ flying was done by MidAtlantic as early as 2002 but those airplanes eventually went to the US Airways Group subsidiary PSA Airlines.
On February 9, 2006, US Airways announced a firm order for 25 Embraer 190 aircraft, a cousin of the 170. However, unlike the smaller E-Jet, the 190 has an 11-seat First Class cabin and is operated by mainline employees under the US Airways banner. On May 28, 2006, MidAtlantic stopped operating.
From Wikipedia’s article on MidAtlantic Airways, shared under CC BY-SA 4.0.4