Amoco-1932 
1932 - 1945
Amoco-1946  
1946 - 1960
 American
1961 - 1974
 Amoco-1971
1974 - 2001

Amoco, (originally Standard Oil founded in 1889 in Indiana), was founded in Baltimore, MD in 1910 and was incorporated in 1922. It operated under the Amoco name from 1928 to 1960.  From 1961 to 1974 it used the American name and then returned to Amoco.  In 1998 Amoco merged with British Petroleum and through the 2000's BP replaced Amoco signs with there own. 
Maps with years in red are not in my collection - scans of covers have been provided by other collectors.
CoverIcon
1961
CoverIcon
1962
CoverIcon
1963
American Cover Icon 64
1964
American Cover Icon 65
1965
CoverIcon
1966
American Cover Icon 67
1967
 American Cover Icon 68
1968
CoverIcon
1969 
 CoverIcon
1970
American Cover Icon 71
1971
 American Cover Icon 72
1972
American Cover Icon 73
1973
 American Cover Icon 74
1974
 75 Amoco Cover Icon
1975
 75 76 Amoco Cover Icon
1975-76