How the heck do I subscribe to US holiday calendar? I should'nt be so difficult

Look harder, because I found it a long while back.

http://www.apple.com/downloads/macosx/calendars/usholidaycalendar.html

Note that it apparently hasn't been updated since 2007; and in another thread people are complaining that Islamic holdays appear to have been added to it (I haven't checked this one so I don't know if it's the same).

Confirmed, that subscription link contains a wide variety of holidays that many U.S. subscribers would consider to be non-us holidays.