General fact: 1601 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 1601 is the number of forests with 12 vertices.
Trivia: 1601 is a boring number.
Historical date: May 19th is the day in 1997 that the Sierra Gorda Biosphere, the most ecologically diverse region in Mexico, is established as a result of grassroots efforts.