Why did Joseph Priestley leave England for the United States in 1794?

Joseph Priestley fled England for the United States in 1794 due to intense political persecution and social hostility.

Priestley was a vocal supporter of both the American and French Revolutions, a stance that the English government and press labeled as "seditious." This climate of hostility culminated on July 14, 1791, when a "Church-and-King mob" destroyed his home and laboratory. Although he attempted to relocate and continue his work, the conservative reaction to the French Revolution in England intensified, leaving him increasingly isolated and vulnerable. Seeking a more tolerant environment, he emigrated to the United States, where he found the form of government to be "relatively tolerable".1