iCal iMac Lion editing US Holidays

[Bob5545]

Looking at the US Holiday Import that is included with the iCal iMac are listed such holidays as Kwanzaa. To me these are not holidays. I don't even know what some of these are. How do I edit these out, or import a US Holiday calendar with only the traditional US Holidays like Christmas, New Years, etc.

This import is cluttering the calendar with all kinds of obscure holdidays.

Thanks