Which united states supreme court case determined that americans of african ancestry were not, and never could become, citizens of the united states?

 Dred Scott  v. Sandford (1857), commonly referred to simply as "The Dred Scott case."

Details:

Dred Scott was a slave who had been owned by a Missouri man named John Emerson.  Emerson's service in the US military caused him to live for a time in Illinois (which was a free state) and Wisconsin (which was a free territory.  Later, back in Missouri, after John Emerson died, Scott tried to purchase his freedom from Emerson's widow, who refused.  With lawyers' help, he then filed suit to gain his freedom on the grounds that he had lived in a free state and free territory.

The Supreme Court, by a 7 to 2 margin, issued its ruling that Scott was not  entitled to his freedom just because he had lived at some times in free territory.  The Court also ruled that African Americans were not and could never be citizens of the United States, and therefore did not have the legal standing to file such a lawsuit.  The Court further stated that the Missouri Compromise of 1820 had been an overreach of federal government power -- that any states or territories were free to make their own decisions regarding slavery.

The Dred Scott decision was a controversial event which played into the tensions that by 1861 erupted into the Civil War in the United States.

they have different colored collars

answer:

it caused mass african migration, african populations to grow, african empires to topple, and racism against slaves to emerge.

background

early european explorers to the americas likely experienced emotions including awe at the vast "new" environment, amazement at meeting "others," the thrill of the unknown, concern for personal safety, desire for personal reward, and longing for their homeland and those left behind. written and pictorial records attributed to europeans provide the bulk of the records of these early travels. impressions of natives as well as native impressions of europeans are frequently framed in the narratives of the explorers. examination of these records indicates the cautious and curious nature of first encounters.

significance

centuries of ignorance, prejudice, and opinions lacking evidence or scholarly research have tainted traditional views of the earliest meetings between native americans (first nations in canada) and europeans. students may come to recognize how the later period of continued exploration, settlement, and interaction was influenced by these early encounters from the st. lawrence river to georgia.