Now, about MNT, MN, etc. I find MNT for MONTSERRAT AIRWAYS, AMN Alma, MI [Gratiot Community Airport], USA. MMN Stow, MA [Minute Man Air Field], USA. MNA Melangguane, Indonesia. MNB Moanda, Zaire. MNC Nacala, Mozambique. MND Medina, CA, USA. MNE Mungeranie, South Australia, Australia. MNF Mana, Fiji. MNG Maningrida, Northern Territory, Australia. MNH Minneriya, Sri Lanka. MNI Montserrat (Plymouth) [Blackburne], Montserrat. MNJ Mananjary, Madagascar. MNK Maiana, Kiribati. MNL Manila [Ninoy Aquino International Airport], Philippines. MNM Menominee, MI [Menominee-Marinette Twin County Airport] USA.. MNN Marion, OH [Marion Municipal Airport], USA. MNO Manono, Zaire., MNP Maron, Papua New Guinea MNQ Monto, Queensland, Australia, MNR Mongu, Zambia, MNS Mansa, Zambia, MNT Minto, AK [Minto Airport], USA, MNU Maulmyine (Moulmein), Myanmar, MNV Mountain Valley, Australia, MNW MacDonald Downs, Australia, MNX Manicore, AM, Brazil, MNY Mono, Solomon Islands, MNZ Manassas, VA [Manassas Regional Airport/Harry P. Davis Field], USA,
Most of that explains pretty much why Minneapolis chose "MSP".
I guess it is a miracle they didn't wind up in Zaire then.