In September 1992, Mesa negotiated a code-sharing agreement with America West Airlines to operate as America West Express out of its Phoenix hub, serving 12 cities.
These routes were originally from the independent Mesa operation and several Beech 1900D aircraft were painted in the America West Airlines scheme.
The codeshare allowed increased frequency and increased load factors and expansion into several new markets.

In 1995, Mesa created a new subdivision called Desert Sun Airlines and acquired a pair of Fokker 70 jets for use on new America West Express routes from Phoenix to Des Moines and Spokane.
 Desert Sun was merged into the Mesa Airlines division in 1997 and its Fokker 70 aircraft were replaced by Canadair CRJ-200 regional jet aircraft.
The CRJ-200 aircraft also began replacing the Beechcraft 1900D and Embraer EMB-120 Brasilia turboprops.
 The BE-1900Ds were then transitioned over to Mesa's Air Midwest subsidiary.
Beginning in December 1997, Mesa began operating de Havilland Canada DHC-8 Dash 8 series 200 aircraft between Phoenix and Grand Junction followed by many other cities throughout Colorado, New Mexico, Arizona, and California.
In 2003, Mesa Airlines took over the operations of Freedom Airlines and Freedom Airlines' Canadair CRJ-900 regional jets were transferred into the America West Express operation.
The Beech 1900 flights operated by Air Midwest were discontinued on May 30, 2008.

On September 16, 2005, America West Airlines and US Airways completed their merger.
Although the corporate side and operationally, those companies merged, as of May 2008, the two flight operations have not been merged and Mesa continues to code share with the new US Airways Group as US Airways Express under its America West Express codeshare agreement.
It operated CRJ200 and CRJ900 aircraft from hubs in Charlotte and Phoenix, and Dash 8 aircraft from its Phoenix hub until late 2011, when during Mesa's restructuring in bankruptcy, coinciding with United's cancelation of any further CRJ 200 service by Mesa, the CRJ 200's and Dash 8's were removed from service.
By early 2012, the only airframe Mesa uses for the "west" side of US Airways out of its Phoenix hub and the "East" side out of its Charlotte hub is with the CRJ 900.
In September 1992, Mesa negotiated a code-sharing agreement with America West Airlines to operate as America West Express out of its Phoenix hub, serving 12 cities. These routes were originally from the independent Mesa operation and several Beech 1900D aircraft were painted in the America West Airlines scheme. The codeshare allowed increased frequency and increased load factors and expansion into several new markets.
In 1995, Mesa created a new subdivision called Desert Sun Airlines and acquired a pair of Fokker 70 jets for use on new America West Express routes from Phoenix to Des Moines and Spokane.  Desert Sun was merged into the Mesa Airlines division in 1997 and its Fokker 70 aircraft were replaced by Canadair CRJ-200 regional jet aircraft. The CRJ-200 aircraft also began replacing the Beechcraft 1900D and Embraer EMB-120 Brasilia turboprops.  The BE-1900Ds were then transitioned over to Mesa's Air Midwest subsidiary. Beginning in December 1997, Mesa began operating de Havilland Canada DHC-8 Dash 8 series 200 aircraft between Phoenix and Grand Junction followed by many other cities throughout Colorado, New Mexico, Arizona, and California. In 2003, Mesa Airlines took over the operations of Freedom Airlines and Freedom Airlines' Canadair CRJ-900 regional jets were transferred into the America West Express operation. The Beech 1900 flights operated by Air Midwest were discontinued on May 30, 2008.
On September 16, 2005, America West Airlines and US Airways completed their merger. Although the corporate side and operationally, those companies merged, as of May 2008, the two flight operations have not been merged and Mesa continues to code share with the new US Airways Group as US Airways Express under its America West Express codeshare agreement. It operated CRJ200 and CRJ900 aircraft from hubs in Charlotte and Phoenix, and Dash 8 aircraft from its Phoenix hub until late 2011, when during Mesa's restructuring in bankruptcy, coinciding with United's cancelation of any further CRJ 200 service by Mesa, the CRJ 200's and Dash 8's were removed from service. By early 2012, the only airframe Mesa uses for the "west" side of US Airways out of its Phoenix hub and the "East" side out of its Charlotte hub is with the CRJ 900.
Mesa Airlines