Politics and politicians of every stripe always held a central place in LIFE Magazine's mission, as articulated by LIFE founder Henry Luce, "to see life; to see the world; to eyewitness great events; to watch the faces of the poor and the gestures of the proud ... to see and be amazed; to see and be instructed...."
And while the magazine's approach to touchstone events — World War II, the Civil Rights Movement, the Space Race, the Vietnam War — as well as famous (and notorious) public figures cemented LIFE's reputation as the photojournalism publication of the 20th century, its straightforward political coverage was, in its own way, equally powerful. After all, to make politics, and politicians, visually exciting is no mean feat.
In recent years, of course, conventions have come to resemble coronations rather than the passionate, quarrelsome rumbles of old. But as many of the pictures here from Democratic conventions of old attest, every once in awhile the carefully stage-managed spectacle could go thrillingly -- and sometimes, as in Chicago in 1968, frighteningly -- off the rails.
At the 1948 convention in Philadelphia, for example, boisterous Southern delegates -- opposed to the Democratic platform that, in their eyes, attacked the "Southern way of life" -- actually walked out in protest. That same year, the "Dixiecrats" formed the States' Rights Democratic Party and ran their own candidate, South Carolina's Strom Thurmond, for president. (Thurmond won 39 electoral votes in the fall, and nearly scuttled Democratic president Harry Truman's chances at re-election.)
But whether or not the convention is filled with tension or a yawn-fest, every four years, as the delegates don their pins and loud, crazy clothes and wave their flags and pennants, and the states' names bob and weave above the crowd like unimaginatively designed carnival puppets — every four years, we pay attention to the spectacle. Every four years, we listen to the speech-makers who hope and trust that speaking before their party's bigwigs and being seen by millions of people watching on TV will somehow help their own chances on the national stage in the next election, or the one after that. We watch and we listen not because we believe that there will be any stunning upsets or even any especially surprising moments, but because the conventions are probably the best and most efficient way for the average citizen to gauge the mood of both parties.
Here, LIFE.com presents a selection of LIFE's best pictures from the Democrats' national conventions across several decades. Famous Dems are here in abundance -- FDR, Harry Truman, Eleanor Roosevelt, Adlai Stevenson, the Kennedys -- as are other long-forgotten pols who were players in their day and the folks who, in the end, provide both parties' conventions with their real energy and their often surprising level of fun: namely, the shouting, laughing, weirdly garbed, wide-eyed delegates.
The American political process has never been pretty. The photos here, however, remind us that, pretty or not, that process can make for wonderful, memorable imagery.