"The song was inspired by a remark by Dean Holloway, Haggard's lifelong friend and tour bus driver. At the end of a packed two-day recording session at Britannia Studios in Los Angeles, Haggard went to the bus to check on Holloway, who had been minding the bus, and asked him how he was doing. Holloway responded, "I hate this place. I'm tired of this dirty old city." Haggard immediately saw inspiration, and began writing the song, based on Holloway's remark, on a nearby pad of paper. "I'm tired of this dirty old city" became the song's first line. Haggard decided that the chorus should include the narrator talking about moving elsewhere, and asked Holloway where he would rather be, to which Holloway responded, "If it were up to me, it'd be somewhere in the middle of damn Montana." "Somewhere in the middle of Montana" became part of the chorus. Haggard rushed back into the studio, where the band was packing up, and told them to unpack their instruments in order to record one last song; the band recorded the song in one take, with no rehearsal.

Haggard credited Holloway as a co-writer, entitling him to half the royalties for the song, which amounted to around half a million dollars for Holloway."

https://en.wikipedia.org/wiki/Big_City_(Merle_Haggard_song)