And leading all the 78 million Americans born between 1946 and 1964 is Kathleen Casey Kirschling of Cherry Hill, N.J. Born just seconds into Jan. 1, 1946. Perhaps the very first boomer, speculates CBS Sunday Morning contributor Jerry Bowen.
"I know people don't consider us the greatest of generations, but I think we were great," Kirschling says, adding that when she was a child "I wasn't sure I was going to be here. When they said 60, the 6-0, I thought, 'Oh, people die by that time.'"
The population boom began when the troops returned from World War II and started families. It ended 18 years later with the development of the birth control pill.
"It's a generation that grew up in a unique historical moment: at the end of World War II, when there was prosperity, a sense of expectation and hope about the future. So it's a generation that was born with a sense of entitlement," says Steve Gillon, author of "Boomer Nation" and resident historian of The History Channel.
He says the boomers are really two generations.
"Those who are born after 1958 I refer to as shadow boomers," Gillon says. "I think in order to be a genuine baby boomer, you have to have some recollection of the Kennedy assassination.
"The Kennedy assassination is, it's the first event of national significance that people experienced simultaneously and through television," Gillon adds.
Watching television gave boomers across the country a shared experience. "Part of what makes the generation coherent is that it's watching the same things," Gillon says.
But that didn't mean all boomers would follow the same path.
For a certain segment of free-spirited boomers, their most famous crossroad was the corner of Haight and Ashbury in San Francisco. It was the energy behind flower power. The home of sex, drugs and rock and roll. The Grateful Dead lived here and in 1967 it gave birth to the hippie in what became known as "the summer of love."
Those boomer hippies were a cultural curiosity to the older generation, like late CBS newsman Harry Reasoner in a 1967 documentary.
"We would all like to be able to live an uncluttered life," Grateful Dead front man Jerry Garcia told Reasoner. "A simple life. A good life and like, think about moving the whole human race ahead, a step or a few steps. We know what we're trying to do. We're trying to grow up."
As the boomers grew up, they pushed every social hot button and then some. Picking up the civil rights banner. Expanding the universe of choices people have from women's rights to gay rights to abortion. Fighting the war in Vietnam and protesting it at home.
They fought the system and they fought each other. On college campuses across the country the battle lines between left and right were drawn early and shape the red state/blue state political landscape of today.