From the late 19th century, the South used a colloquial term, the one-drop rule, to classify as black a person of any known African ancestry. This practice of hypodescent was not put into law until the early 20th century. Legally the definition varied from state to state. Racial definition was more flexible in the 18th and 19th centuries before the American Civil War. For instance, President Thomas Jefferson held persons who were legally white (less than 25% black) according to Virginia law at the time, but, because they were born to slave mothers, they were born into slavery, according to the principle of partus sequitur ventrem, which Virginia adopted into law in 1662.
When was the "one-drop" rule put into place?
early 20th century.

A zygote initially develops into a hollow sphere, called a blastula, which undergoes rearrangement and differentiation. In sponges, blastula larvae swim to a new location and develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement. It first invaginates to form a gastrula with a digestive chamber, and two separate germ layers an external ectoderm and an internal endoderm. In most cases, a mesoderm also develops between them. These germ layers then differentiate to form tissues and organs.
What are the 2 germ layers formed by most blastula?
an external ectoderm and an internal endoderm

The Embargo Act of 1807, adopted during the Napoleonic Wars, and the War of 1812 significantly curtailed Boston's harbor activity. Although foreign trade returned after these hostilities, Boston's merchants had found alternatives for their capital investments in the interim. Manufacturing became an important component of the city's economy, and by the mid-19th century, the city's industrial manufacturing overtook international trade in economic importance. Until the early 20th century, Boston remained one of the nation's largest manufacturing centers and was notable for its garment production and leather-goods industries. A network of small rivers bordering the city and connecting it to the surrounding region facilitated shipment of goods and led to a proliferation of mills and factories. Later, a dense network of railroads furthered the region's industry and commerce.
What act cut down on Boston's harbor activity?
The Embargo Act of 1807