Theodore Roosevelt waves to the crowd. (Courtesy of Library of Congress Prints and Photographs Division via PBS/Courtesy of Library of Congress Prints and Photographs Division via PBS)

Let’s start with the end. When it’s over — when you make it through the marathon that is Ken Burns’s beautiful, seven-part documentary “The Roosevelts: An Intimate History,” which begins Sunday night on PBS — you may find yourself with a lingering, nebulous grief. You’re sorry it’s over. You’re sorry they’re over. You’re sorry a certain expression of American ideals is, or often appears to be, completely over.

My study habits haven’t improved since college; like an idiot, I put off watching all 14 hours of “The Roosevelts” until I absolutely had to watch them on a deadline binge this week. Yes, the entire series sat on my desk for most of the summer, while there was still plenty of time to savor it. When I emerged from my office for a break, midway through the amplified noise of World War I, a co-worker reminded me (spoiler alert) that all of the major players eventually die, so why bother watching the whole thing? Why not skip ahead or skim through most of it?

Because I was absorbed. Within the first hour, “The Roosevelts” will probably have you hooked in a way that Burns and his collaborators haven’t quite achieved since 2007’s “The War.” Unlike the intimidating climb offered by “National Parks” or “Prohibition,” you easily glide through “The Roosevelts’ ” sublimely constructed narrative arc. The series is among Burns’s best works.

Thoroughly invested, I teared up every time one of the Roosevelts passed: when Theodore died in his sleep in January 1919, still entertaining a fantasy of a political comeback; when an ailing Franklin suffered a brain hemorrhage at his Warm Springs, Ga., retreat in April 1945; and finally when Eleanor, the best of the bunch, died peacefully in her bed in November 1962. I was also moved when they lost children, friends or parents. “The Roosevelts” delivers on its subtitle, drawing such a full and close portrait of the extended clan and their social and political circles that a viewer can’t help but feel connected to them, faults and all.

“The Roosevelts” also leaves a viewer with another, more subtle kind of grief, a sense of loss about the world they inhabited and the country they helped sustain. It can’t be a mistake that Burns’s saga, straddling the century from Theodore’s birth to Eleanor’s death, provokes a sense of wonder about how, in the Roosevelts’ time, the United States outgrew a few of its inherent dysfunctions and managed to face its most dire crises.

President Franklin Roosevelt at his home in Hyde Park, N.Y., in 1937. (Courtesy of Franklin D. Roosevelt Presidential Library via PBS/Courtesy of Franklin D. Roosevelt Presidential Library via PBS)

The series is airing just as the country seems least concerned about the common man, the fair shake and our shared well-being; we’re looking back at FDR while all that beautiful New Deal infrastructure now begs for upkeep; we’re looking back at Teddy while our magnificent West bakes dry in a sullied environment.

When at last you turn the television off and return to the present, it’s tempting to wallow in embarrassment over how little our political leaders of either party accomplish now; how pathetic the whole game has become; the sorry ways in which we measure success. None of this is presented as such by the fastidiously objective Burns or the elegant and simple narration of the series, read by Peter Coyote and written by Geoffrey C. Ward. You just get there all on your own.

Besides Coyote and Ward, the rest of the Ken Burns gang is on hand, too: Doris Kearns Goodwin, David McCullough, George F. Will and the usual panoply of historians supply necessary and trenchant shorthand; Paul Giamatti reads letters and speeches in the voice of Teddy Roosevelt; Edward Herrmann supplies his familiar patrician FDR tone; Meryl Streep, naturally, gives herself entirely to the task of becoming the voice of Eleanor. The photographic and motion-picture archives keep your eyes fixed on the screen; a viewer is tempted to reach for the smartphone only occasionally, usually to look up and confirm some startling fact or another.

Much of “The Roosevelts” is obviously preoccupied with the enormous egos and capabilities that defined both Theodore (a Republican who was president from 1901 to 1909) and his fifth cousin Franklin (a Democrat who was president from 1933 to 1945). But, just as often, it’s a study in how everyday Americans responded to leaders they could believe in.

During one of his “fireside chat” radio broadcasts at the onset of World War II, FDR asked listeners to get a map and follow along as he explained both the Pacific and European theaters to them. The people went out and bought maps. They followed along. They listened to their president, and by and large they trusted him. By 1941, they’d already bought into and benefited from his New Deal. The broadcast was not followed by a news cycle of contrary analysis and fact-checking of the president’s every word. In the present context, it’s hard to imagine that sort of devotion.

Ward’s script has done a marvelous job of making the history accessible and the subjects thoroughly — and at times achingly — human. Come for the explanation of the Hepburn Act; stay for the tales of increasing acrimony between the Oyster Bay branch of the Roosevelts and the Hyde Park branch. (That rift, like the Great Depression, was only ever truly repaired by the cooperative work of fighting World War II.)

The documentary is probably not as probing as some viewers will want it to be when it combs the deeply personal. Were Eleanor’s close friendships with women also sexual relationships? So much discussion about that over the years has obscured the fact that she also made very close friends of men while her husband was president, to whom she wrote letters that were just as fond as those she wrote to her women friends. One thing is made clear in the documentary: She was devastated by Franklin’s affair with her social secretary, a relationship that would hurt her feelings all over again 20 years later.

Delegate Eleanor Roosevelt at a meeting of the United Nations in 1947. (Courtesy of Franklin D. Roosevelt Presidential Library via PBS/Courtesy of Franklin D. Roosevelt Presidential Library via PBS)

There’s also a whole lot to consider here about the wealth gap. The Roosevelts’ fortunes enabled them to do whatever they wanted all their lives. This supplies a great deal of that PBS-style fascination (let’s call it the “Downton Abbey” factor) for gorgeous summer estates and fabulous multistory Manhattan townhouses. Much of “The Roosevelts” would be right at home on HGTV.

Somehow Teddy, Franklin and Eleanor — each in his or her own way — reckoned with being rich and arrived at a worldview that included and expanded the rights of the working poor and transcended political bent. Even though Burns never sets out to bring his projects into a current context (or beat his viewers over the head with an editorial message), one is still left wondering: What made these particular rich people so much nicer than the fat cats we read about today?

The Roosevelts: An Intimate History

(seven episodes; 14 hours total)
begins Sunday and airs nightly (through Sept. 20) at 8 p.m. on WETA and MPT.