From 1946 to 1986, the original Frontier Airlines, Denver's hometown carrier for 40 years, carried 87 million passengers.
Back in 1948, Kimberly-Clark began providing shuttle services on various routes to its own employees, and formed K-C Aviation in 1969.
Midwest Express Airlines was launched by K-C Aviation and Kimberly-Clark in 1984 with just two DC-9's and 83 employees.
In 1986, Frontier Airlines was incorporated into Continental Airlines, marking the end of the first Frontier Airlines.
McDonnell Douglas MD-80s started to be added to the Midwest Express Airlines fleet in the early 1990s.
In 1994, the new Frontier Airlines was founded in response to the void left by Continental Airlines' (now United Airlines) 1993 shutdown of its Denver (Stapleton) hub. The new airline took off in July 1994 utilizing Boeing 737 jetliners.
In 1995, Midwest Express Airlines became a publicly traded company.
By 2001, the new Frontier Airlines was on Fortune magazine's list of fastest-growing companies.
Eight years later, the name was simplified to Midwest Airlines.
In April 2005, Frontier Airlines officially became an all-Airbus fleet, retiring its last Boeing 737.
In late 2005, the Board of Directors of Midwest Air Group decided to sell the company, but it took some time for this to become reality.
In 2008, TPG Capital purchased Midwest Airlines and returned it to being a privately held entity, and Frontier Airlines filed for bankruptcy.
One year later, Republic Airways Holdings, a publicly held company, acquired both airlines, Midwest for $31 million and Frontier for $109 million, plus the assumption of $1 billion in debt and aircraft lease obligations.
Midwest and Frontier became wholly owned subsidiaries of Republic Airways, but each continued to operate under its own branding.
In the Spring of 2010, Republic Airways Holdings announced that the Frontier and Midwest Airlines brands would merge under the Frontier Airlines name, with the iconic Midwest cookie and the slogan of Midwest Airlines, "The Best Care In The Air", incorporated into the Frontier brand.
In the fall of 2010, Frontier and Midwest officially became one airline when the Midwest’s website, midwestairlines.com, was shut down, and Midwest's YX code was retired.
In 2011, World Travel Awards, the travel industry awards program that has been described by the Wall Street Journal as the “Oscars of the Travel Industry”, named Frontier Airlines “North America’s Leading Low-Cost Airline”.
In 2012, Frontier Airlines introduced onboard Wi-Fi on the airline’s Embraer 190 fleet.
In July 2013, Frontier Airlines announced new nonstop seasonal service between Denver and Montego Bay, Jamaica, with weekly nonstop flights beginning on December 22, 2013.
Frontier Airlines, operating from its hub at Denver International Airport, offers service to more than 80 destinations in the United States, Costa Rica, Mexico, Jamaica, and the Dominican Republic.
During its history, Midwest was involved in a single fatal accident. In early September, 1986, a Douglas DC-9 flying as Midwest Express Airlines Flight 105 crashed shortly after takeoff from General Mitchell Airport, Milwaukee, Wisconsin, killing all 31 people on board.