The later half of the 18th century was a time of political upheaval in the United States. In the midst of cries for relief from British rule, people pointed out the apparent hypocrisies of slave holders' demanding freedom. The Declaration of Independence , a document that would become a manifesto for human rights and personal freedom, was written by Thomas Jefferson , who owned over 200 slaves. Other Southern statesmen were also major slaveholders. The Second Continental Congress did consider freeing slaves to disrupt British commerce. They removed language from the Declaration of Independence that included the promotion of slavery amongst the offenses of King George III . A number of free Blacks, most notably Prince Hall —the founder of Prince Hall Freemasonry , submitted petitions for the end of slavery. But these petitions were largely ignored. 
It's unclear why these differences exist, but access to and attitudes toward prevention and treatment may offer some explanation. Several studies have found that African American patients are more likely to be diagnosed after the cancer has spread beyond the colon, making it more difficult to treat successfully. Another study found that African Americans were half as likely as Caucasians to have undergone colonoscopy screening, even after accounting for differences in education, income, and health insurance status. In addition, African Americans with colorectal cancer are less likely than Caucasian patients to receive recommended surgical treatment and therapies.