PHILADELPHIA (CBS) - The three-day weekend has brought lots of visitors to Philadelphia’s historic sights but there’s some confusion about what holiday we’re actually celebrating.

What do you call this holiday? Most people say it’s President’s Day.

“Officially, this is referred to as Washington’s birthday,” Mark Kehris of the National Constitution Center explains.

That’s right. This is not, technically speaking, a celebration of the entire executive branch of government — just the original.

“The policy of the government is that, if a holiday is known by different names in different states, they choose the one that’s going to be applicable all across the board,” Kehris said.

Washington’s birthday became a federal holiday in 1885. Abraham Lincoln’s birthday was a holiday in some places but not the southern states whose secession hopes he dashed. So when the date changed as part of the Uniform Monday Holiday Law, efforts to make the day honor both men failed, but popular culture has accomplished what federal lawmakers could not.

Reported by Pat Loeb, KYW Newsradio