How long does copyright last?
Originally, copyright lasted for 14 years, but now, things have changed.
Assuming the copyrighted work was not a work-for-hire, copyright lasts for the life of the author plus 70 years in the United States. To illustrate: if a twenty-year-old person created something this year, 2013, and then lived to be 95, the copyright on the work would not expire until the year 2158, or 145 years from now.
Works-for-hire have a copyright term of 120 years.
You may wonder why I didn't calculate from the date of publication. Under U.S. copyright law, copyright is not based on the publication date but on the date when the work is "fixed." Copyright is also conferred automatically. It does not have to be registered, but registration is recommended.