He was then elected to the Maryland Senate from 1983 until his death in 1997, representing District 35, which covers Harford and Cecil Counties.

Upon his death, Democratic Governor Parris Glendening appointed former State Delegate, Donald Fry, to be Senator Amoss' successor.

[1] Fry was defeated by Republican challenger J. Robert Hooper in the 1998 general election by 10 percentage points.

Maryland passed the William H. Amoss Organ and Tissue Donation Act of 1998 in his honor.

[3] Additionally, there is an award named in his honor - the Senator William H. Amoss Legislator of the Year Award, which is awarded annually and also the State Fire, Rescue, and Ambulance Fund was renamed the Senator William H. Amoss Fire, Rescue, and Ambulance Fund in recognition of his efforts to provide fire, rescue, and ambulatory assistance to local departments.