Both. They are two differents ways of writing the dates. The first one (March, 1st ) is American English; the second one (1st March) is British English

Olga's right - I'll even add that most of the English-speaking world put the day first, and I've even noticed that some US citizens helpfully switch to the "day first" format when writing to people outside the USA. The "month first" method is slightly more economical, but it's only a US thing.