Let's look at some of the most well known historic instances of racism:

• Slavery: an institution that cruelly subjugated black people. It was enforced by the provisional governments in North America before the US revolution, enshrined into the Constitution, and required a civil war to end. People in power: white men
• The Trail of Tears: an illegal genocide of several Native American tribes, which had them march over 1000 miles to Oklahoma. People in power: white men
• The Chinese Exclusion Act: this was the first time the US border was strictly enforced. It was designed to stop people from China and the Philippines from entering the US, on racist grounds. It was used to deport Chinese people that had just finished building the Transatlantic Railroad. People in power: white men
• Redlining neighborhoods: the US and banks worked together to provide cheap loans for buying houses and starting businesses. Zip codes were classified as low risk, medium risk, and high risk. It was never stated outright, but there was high correlation between black people living in an area and being associated with more risk. Black people almost never qualified for a loan, because their zip code was in a "high risk" (redlined) neighborhood. People in power: white men
• Building the national highway network: when deciding where to build highways, white neighborhoods were usually avoided and instead divided or destroyed minority neighborhoods. People in power: white men
• Jim Crow: the famous "separate but equal" laws, which controlled several aspects of black people's personal lives and legally entrenched them as second class citizens to white people. People in power: white men