As the nation gears up for the political conventions over the coming weeks, you can almost cut the tension with a knife. A butter knife, that is. Make that a plastic butter knife.

Yeah, political conventions aren't what they used to be. The decisions once made in smoky back rooms by the political power brokers are virtually gone. Yes, we await to hear who the vice presidential candidates will be, but even that decision won't necessarily be unveiled during the conventions.

There was a time when primaries were political experiments and the conventions reigned supreme. Here's a short list of some that changed the course of history.

1912 Republican Convention

Theodore Roosevelt had always been a candidate for change. His opponent for the Republican nomination, the incumbent and his hand-picked successor from 1908, William Howard Taft, was not.

For the first time in history, the Republican party hosted primary elections, of which Roosevelt won handily, even thumping Taft in Taft's home state of Ohio. However, there were only 12 primaries, and although Taft was behind heading into the convention, his forces ran the machinery of the convention.

In a highly contentious convention in Chicago, Taft received virtually all of the remainder of delegates. The ensuing split - Roosevelt went on to form the Bull Moose Party and the closest thing to a third party victory in the history of modern politics - guaranteed victory for the Democratic candidate, Woodrow Wilson.

1948 Democratic Convention

The presidential race of 1948 is perhaps the most fascinating of the 20th Century. The shocking upset of an incumbent over a Repubican dream team, immortalized in the famous photo of Harry S Truman holding up the newspaper with the banner headline "Dewey Defeats Truman" is perhaps the most lasting image of American presidential politics.

But the Democrat Party's nomination process leading up to that moment was equally noteworthy. In the first election of the postwar era, the Democratic party found itself in a predicament.

Since the days of Abraham Lincoln, it had dominated the South. However, the more liberal arm of the party wanted the party to more strongly embrace a growing civil rights movement.

In the end, the liberals won out barely by the traditional Southern Democrats. In response, the entire Mississippi delegation and half the Alabama contingent walked out of the convention.

Truman embraced the new civil rights movement, issuing executive orders for equal opportunity in the armed forces and civil service for people of color. Outraged, a new party rose out of the South, launching the national political career of Strom Thurmond of South Carolina, the Dixiecrat's nominee for the president.

Despite the split, Truman defied the odds and won the presidency. Civil rights, however, failed to garner much momentum, staying largely on the backburner until the 1960s.

1964 Republican Convention

The godfather of the conservative movement in the Republican party, Barry Goldwater faced the battle of a lifetime in his own primary.

Political icon Nelson Rockefeller, whose popularity with moderates and liberals in the Republican party was unquestionable, seemed like the perfect fit for the 1960s. But Rockefeller's personal life, combined with a record as governor that fit more closely with the Democrats than Goldwater's, proved to be his undoing.

Meanwhile, Goldwater gave no quarter, noting that there was no virtue in moderation. His views staunch views against communism and his hardline conservative values managed to sway his party's nomination.

And while his message rang out of tune in the general election in November where he was crushed by the incumbent Democrat, Lyndon B. Johnson, Goldwater's message remained as a foundation upon which Ronald Reagan would build his successful campaign for the presidency in 1980.

1968 Democratic Convention

The age of cynicism had arrived in one sudden violent movement known as the the 1968 Democratic Convention.

The Civil Rights Movement, led through tumultuous times by Martin Luther King and his steady practice of nonviolent civil disobedience, exploded earlier in the year with his assassination in Memphis. More than 20 blocks of Chicago burn, as do communities nationwide.

The Vietnam War, which had escalated to a level that forced President Lyndon Johnson to not seek the party's nomination, had led to further unrest that spilled over into protests nationwide and were in full force at the convention.

Meanwhile, Chicago Mayor Richard Daley promises to meet force (or even non-force) with even more force. Protesters clash with local police and national guardsmen. Chaos prevails.

The arrest count for Convention Week disturbances is 668. Hospitals treat 111 protesters, and many more are likely injured. Medical teams from the Medical Committee for Human Rights estimated that their medics treated more than 1,000 protesters at the scene. As for the police department, it reports that 192 officers were injured, with 49 officers seeking hospital treatment.

The chaos, the violence and the eventual failure of the Democratic party lead to further disillusionment of many baby boomers with the political and societal structures.

And then came Watergate.

1976 Republican Convention

Often believed to be the last real convention, the 1976 Republican Convention opened with the equal possibility that either incumbent Gerald Ford or challenger Ronald Reagan could win.

Although Ford led Reagan heading into the convention in the number of dedicated delegates, neither had the required amount to win the nomination. The two arrived at Kansas City early to try and woo those still in play.

In the end, Ford won out, possibly because of a misstep by Reagan, who had promised to name Sen. Richard Schweiker and his running mate. The moderate Schweiker caused some to defect from Reagan.

When the vote came in, Ford won the nomination with 1,187 votes to Reagan's 1,070.

Reagan stepped aside graciously. And in his concession speech, he stirred the Republican base so strongly that not only did he ensure his nomination in 1980, but he left delegates on the floor wondering whether they had chosen the right candidate.

In the end, it turned out they didn't as Ford lost to a virtual unknown in George governor Jimmy Carter in the general election.