From President Kennedy onward presidents "all have this shared belief in a call to the American people" to engage in civic-minded activity, says Michelle Nunn, the CEO of Points of Light. The fact that presidents of both political parties, right up to Mr. Obama, have been strong supporters of volunteerism "shows the common ground around service," she says.
Volunteering can be a great antidote to the discouragement of sharply partisan politics. "People are disheartened about the polarization they see reflected in the political landscape [today]," Ms. Nunn says. "So one of the themes of the Martin Luther King Jr. weekend is 'unite in America's service.'
"And I do believe that if you look at the history of this country, and you think about one of the defining characteristics of this country, it has been … that we have a great civic spirit and a great sense of citizenship and service."
Volunteering is a reminder, Nunn says, "that there's a lot more that we can act upon and create change around than what seems to be the paralysis in Washington."
The economic hard times of recent years have upped the need for volunteers – and Americans have been responding, she says.
"Everyone knows someone who's been struggling," Nunn says, "so I think it makes people more empathetic."
While financial philanthropy is "critical and important," she says, it's been shown that "people who volunteer their time are more likely to give more [financial donations], and more often, than people who don't."
Volunteers also gain a sense of satisfaction that can't be underestimated. And volunteering means making new connections and new friendships – it's "being about something that's larger than yourself," she says. "And most important is the feeling of having made a difference. All the great faith traditions point you to [the idea] that people find meaning in life by being of service to others."