Simplify the following text for a Grade 6 native English-speaking person.
Original: He worked in the United States House of Representatives from March 4 , 1799 , to June 7 , 1800 , and , under President John Adams , was Secretary of State from June 6 , 1800 , to March 4 , 1801 .
Simplified: He was Secretary of State under President John Adams from 1800 to 1801 .