Colombia is the name of the South American country, and it is misspelled shamefully often, as here: "Next is a piece about rebels in Columbia" (Boston Globe). The problem arises because the man known in his native Italy as Cristoforo Colombo became in English Christopher Columbus. Thus words derived from his name in English –Columbia University, the District of Columbia, British Columbia– carry a u, but those originated by speakers of Romance languages are spelled with an o in the second syllable. In all events, misspelling a country's name is about as inexcusable a mistake as a journalist can make.
Bill
BRYSON, Bryson's Dictionary of Troublesome Words, Broadway Books, Nueva York,
2002.