Key Lime Air (KG, Denver Centennial) will commence Essential Air Service (EAS) flights on the Thief River Falls to Minneapolis St. Paul International route from June 1, 2020, replacing the existing turboprop service operated by Boutique Air (4B, San Francisco). The current EAS contract with Boutique Air, which operates from Thief River Falls 18x weekly with its PC-12 fleet, is set to end on May 31 and no service hiatus is expected.

The new two-year contract, awarded by the US Department for Transportation (DOT), will attract a first-year annual subsidy of USD3,956,517 and a second-year annual subsidy of USD4,035,647, and will be operated under Key Lime's Denver Air Connection (DAC) brand. The 12x weekly service will be flown by either Key Lime Air's 30-seat Do328-300s or 50-seat E145s.

Other carriers that expressed interest in operating the contract included Air Choice One (St. Louis Lambert International), which proposed an 18x weekly service with its 19-seat Beech 1900Cs, and Southern Airways Express (9X, Memphis International), which suggested an 18x or 21x weekly service with its nine-seat Cessna (single turboprop) 208B Caravans.

In November 2019, the DOT requested community comments regarding this air carrier-selection case. In response, Joe Hedrick, Airport Manager of Thief River Falls Regional Airport, expressed his support for DAC. In his letter to the DOT, Hedrick cited reliability as being the most critical factor for the airport authority, and said: "as experienced with the community's previous airlines, without reliability - qualities such as aircraft type, frequency, interline arrangements, or the subsidy required - are meaningless."

Earlier in 2019, the airport authority expressed its concerns to the DOT over Boutique's completion rate and cancellations and other issues of concern, which the authority states were acknowledged, but not adequately addressed, by the airline. The Thief River Falls community's largest employer, Digi-Key Corporation, informed the DOT and the airport authority that it no longer recommended their vendors, suppliers, or employees fly in or out of the airport because of concerns about Boutique's reliability.

In awarding the EAS, the DOT said: "DAC meets all the selection criteria the Department must consider when selecting an air carrier to provide subsidized EAS. DAC received community support, has an interline agreement with United Airlines (UA, Chicago O'Hare), and has provided reliable service at other EAS communities. Also, with more seats available than other proposals, DAC has the potential of increasing passenger usage. DAC is allocating USD20,000 toward marketing its service and will be matched by the Thief River Falls Regional Airport marketing budget of USD23,000."

Key Lime Air operates five Do328-300s, one E120(ER), three E145(LR)s, and twenty-five Metroliners.