- Mar 1 Michigan becomes 1st English-speaking jurisdiction to abolish the death penalty (except for treason against the state)
- Mar 3 US Post Office Department is authorized to issue postage stamps
- Mar 3 9th Grand National: Denny Wynne aboard Mathew IRE wins
- Mar 7 US General Scott occupies Vera Cruz Mexico
- Mar 10 1st money minted in Hawaii
- Mar 14 Premiere of Verdi's "Macbeth" at the Teatro della Pergola, Florence
- Mar 18 1st Dutch public telegram
- Mar 25 Pope Pius IX encyclical "On aid for Ireland"
- Mar 29 12,000 US troops capture Vera Cruz, Mexico