This remained the core of the company's business throughout its history, although the airline also expanded into a number of other geographic areas over the years.

On October 21, 2000, Big Sky began new service between Montana and north Texas via southeastern New Mexico with a Dallas/Ft.

On December 21, 2006, a press release announced that Big Sky would become a Delta Connection carrier via a code share agreement with Delta Air Lines using eight Beechcraft 1900D turboprops operated from Boston's Logan International Airport (BOS).

This was due to the loss of the Delta contract, unusually bad weather, disappointing revenue and record-high fuel prices.

The remaining Beechcraft 1900D aircraft were planned to be auctioned off and proceeds returned to MAIR holdings stockholders.

[11] Big Sky's final scheduled flights arrived in Billings on the morning of March 8, 2008; that morning, the three final flights marked the end of the airline by performing a joint flyover of the Billings airport prior to landing.

Destination information is taken from various Big Sky Airlines route maps:[13] Arkansas Colorado Idaho Minnesota Missouri Montana New Mexico North Dakota Oklahoma Oregon South Dakota Texas Washington Wyoming Maine Massachusetts New Brunswick New Jersey New York Ohio Pennsylvania Quebec Vermont In January 2000, the Big Sky Airlines fleet consisted of 14 Fairchild Swearingen Metroliner Metro III and Metro 23 aircraft.

However, the air carrier then removed the Metro propjets from its fleet and in January 2008 was operating Beechcraft 1900D turboprops with 10 aircraft in the fleet: Big Sky previously operated Handley Page Jetstream propjets as well as Cessna prop aircraft during the late 1970s.

[15] By 1987, the airline was operating British Aerospace BAe Jetstream 31 propjets on its flights as a Northwest Airlink air carrier.