The best method to contact a member of Congress is to either complete the form on the contact page of their website or call the appropriate regional office listed on their website. Please note security measures can cause significant delays to the delivery of postal mail.
When writing to either a U.S. Senator or a U.S. Representative, address the envelope and the inside address of the letter to The Honorable (Full name of Senator or Representative), as in The Honorable Carl Levin or The Honorable Justin Amash. Write the salutation of your letter as “Dear Senator (Surname)” or “Dear Representative (Surname)”.