The duration of copyright is measured from the date that copyright protection begins.  For works with copyright-begin dates during 1977 and earlier, the number of years are fixed so that the length of each term will be same for all works with copyright-begin dates that same year.  For works with copyright-begin dates in 1978 and later, the lifetime of the author (or last-surviving author in case of multiple creators) may be a factor.  The graph appearing below will enable you to establish the length of the terms.

The copyright-begin is on the “x” axis (the one running up and down, vertically); the “y” axis (the one running across left to right) identifies where terms of copyright begin and end.  Place your mouse over the colored bars to obtain specific information about the terms in the form of written numbers of statements.  (If you are unable to see the overlays when you place the mouse atop the color bars, consult the text immediately below the table for an alternative source to obtain the information.)