It is included in the Federal Aviation Administration (FAA) National Plan of Integrated Airport Systems for 2021–2025, in which it is categorized as a non-hub primary commercial service facility.

[5] The first airfields in the Keweenaw Peninsula were, as common at the time, near the shoreline; several are known to have existed on both sides of the Portage Canal, with airmail and ad hoc passenger service to Chicago's Meigs Field.

[7] Despite strong community support for Mesaba's service, the FAA instead selected Skywest Airlines, operating as United Express, making two daily flights to Chicago.

According to the airport authority, it stands for Canadian Michigan eXchange,[10] as the airfield would serve as an emergency diversion point for flights from cities like Toronto to western Canada.

A second explanation, possibly apocryphal, references the once-common practice of appending "X" to two-character weather station codes, such as seen, for example, in Los Angeles (LAX) and Portland, Oregon (PDX) - with "CM" in this case referencing nearby Calumet.