I'm not Travis and I'm not an attorney, but a web search for copyright limits gave me this.

The Copyright Term Extension Act of 1998, alternatively known as the Sonny Bono Copyright Term Extension Act or pejoratively as the Mickey Mouse Protection Act, extended copyright terms in the United States by 20 years.

Before the act (under the Copyright Act of 1976), copyright would last for the life of the author plus 50 years, or 75 years for a work of corporate authorship; the act extended these terms to life of the author plus 70 years and 95 years respectively.

The act also affected copyright terms for copyrighted works published prior to January 1, 1978, increasing their term of protection by 20 years as well. This effectively 'froze' the advancement date of the public domain in the United States for works covered by the older fixed term copyright rules. Under this act, no additional works made in 1923 or afterwards that were still copyrighted in 1998 will enter the public domain until 2019.

Unlike copyright extension legislation in the European Union, the Sonny Bono Act did not revive copyrights that had already expired. The act did extend the terms of protection set for works that were already copyrighted, and is retroactive in that sense. However, works created before January 1, 1978 but not published or registered for copyright until recently are addressed in a special section, and may remain protected until 2047. Sec. 303. The act became Public Law 105-298 on October 27, 1998.

Does that help?

Before 1976, life of the author plus 50 years. Now life of the author plus 70 years.

Works that were copyrighted 1923 or after and still copyrighted in 1998 will enter the public domain until 2019.

So if you have a 1982 book, and the author died in 1990, published by an individual, that means you can copy it to the web, in the year 2060.