My son is writing a formal letter to his governor, state senator and representative, and U.S. senators and representative, requesting assistance to enter the military. He will be sending the same letter to each person. Does he address the letter to the governor and cc: the rest, or does he include each person's address at the top of the letter (approximately seven different addresses), or does he change the address and salutation for each individual?
He should send a letter to each individually. There is no reason why he should not indicate that copies have gone to all the others by a cc at the end [making sure he omits the person addressed at the head of the letter].