Copyright Act of 1790
Term of 14 years
Renewal of 14 years

Copyright Act of 1831
Term extended to 28 years
Renewal of 14 years

Copyright Act of 1909
Term of 28 years
Renewal extended to 28 years

Copyright Act of 1976
Life of the author, plus 50 years (generally)
75 years from date of publication or 120 years from date of creation (anonymous works, pseudonymous works, and works made for hire)

Sonny Bono Copyright Term Extension Act (1998)
Life of the author, plus 70 years (generally)
95 years from date of publication or 120 years from date of creation (anonymous works, pseudonymous works, and works made for hire)

Sonny Bono Copyright Term Extension Act (1998) is what Disney was able to lobby for to extend the life of Mickey for another 20 years. It expires in 2024. But trademark will still be valid.