On Sunday, February 10, 2013 3:35:37 AM UTC-5, djmpark wrote: > With the Show statement Mathematica picks up the Options from the first plot > in the Show statement and they override Options from subsequent plots. This > doesn't make a lot of sense and confuses many users. So, for example, if you > had an Epilog Option in the second plot that logically went with the second > plot, you would have to shift it to the first plot. However, you can also > put Options at the end of the Show statement and these take precedence.
The suggestion to move the Epilog/Prolog to the first plot is helpful. Still, after all this discussion, I am inclined to say that comparison with the simplicity of mpl's axvline suggests that there is a missing feature in Mathematica: perhaps, a keyword for Rectangle coordinates to get the full graph extent. In economics and finance graphs, this is a very common need.