Songs don't have to be popular to be important. Still, as the following look at 20 Protest Songs That Changed History so clearly shows, they often are.

Mainstream America has embraced anthems that spoke to rising or initially unpopular ideas, forming a rallying cry for counterrevolutions against everything from war to racism. In some cases, the songs became synonymous with their moment, inseparable from the times and the fight for peace, justice and equality.

Tragedy sometimes proved to be a creative spark, including 1970's Kent State shooting where the Ohio National Guard killed four young Americans while dispersing student demonstrators. Human rights for minorities, for women, and for workers became topics of conversation – and soon made their way to the hit parade. The country – and singer-songwriters – were galvanized by things like the trial of the Chicago Seven, a group of anti-war protesters who were charged with inciting a riot. The assassinations of Martin Luther King Jr. and other key leaders moved others to place pen to paper.

Yet their messages were often transcendent, rather than being tied to any specific era. Sadly, each successive generation has found their own meaning in songs like "Give Peace a Chance." Many of them can be heard at movement gatherings to this very day.

Perhaps that's because there are few easier, more effective ways to communicate complicated political messages. Some are so catchy that listeners might miss their hard truths.

Stacker compiled the following list of 20 Protest Songs That Changed History using official documents from these movements, historical archives, and various other online sources. These stories, like the lyrics, continue to inspire:

20 Protest Songs That Changed History

Here's a look back at songs that played a key role in political movements compiled by Stacker.

Gallery Credit: Stacker

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