US Calendar Federal Holidays Only

The US Holiday Calendar provided by EM Client contains both national holidays and a large numbers of state holidays which are meaningful only to people who live in those states, and which clutter up the calendars of people who don’t.

Could you offer an alternate US holiday calendar with only US Federal holidays? There are only about thirty Federal holidays on which banks and government agencies are closed, and it would be helpful to have them on my calendar without also having holidays occurring only in locations hundreds or thousands of miles away.

I’ve tried to add .ics calendars based on this principle, but keep getting told that they are in an invalid format.