general_fact: 2830 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
math_fact: 2830 is an uninteresting number.
trivia: 2830 is an uninteresting number.
historical_date: September 30th is the day in 1935 that the Hoover Dam, astride the border between the U.S. states of Arizona and Nevada, is dedicated.