Black protest music in the US has roots that are hundreds of years old. From the early days of slavery, enslaved black Americans created songs, often using religious themes and imagery, but with coded messages of resistance. For example, the pre Civil War era spiritual Oh Mary Don't You Weep contains the repeated refrain "Pharaoh's army got drowned." This is a reference to the defeat of the slaveowning Egyptians in the Biblical book of Exodus, and the subsequent emancipation of the enslaved Israelites --the coded message is clear.
During the Harlem Renaissance, Billie Holiday released the stunning anti-lynching anthem "Strange Fruit," as well as the milder, but still biting "God Bless the Child."
Many of the old slave-era songs were reimagined and re-purposed during the 60's Civil Rights' Movement, and new songs in similar styles were created or adapted. Folk singer Odetta ("Oh Freedom!") and gospel superstar Mahalia Jackson ("We Shall Overcome") were singers who were active in the movement both on and off wax, as was jazz singer Nina Simone ("Mississipi Goddam").
In the later 60's into the 70's, the black power movement coincided with the migration of protest imagery into popular music, and any number of top-selling black artists incorporated social messages into their work. Some of these include:
- Sam Cooke ("A Change is Gonna Come")
- Isley Brothers ("Fight the Power")
- The Temptations ("Ball of Confusion")
- Sly and the Family Stone ("Everyday People")
- Edwin Starr ("War")
- Isaac Hayes ("Soulsville")
- Solomon Burke ("Maggie's Farm")
- The Staple Sisters ("Freedom Highway")
- The Pointer Sisters ("Yes We Can Can")
- War ("The World is a Ghetto")
- Smokey Robinson ("Abraham Martin and John")
Most of these artists tended to do protest songs, not protest albums. Even Nina Simone, who did innumerable well-known protest songs, spread them out across many different albums. Your best bet might be compilation albums, like Simone's recent "Protest Anthology," or any of several Civil Rights Movement song compilation albums.