The graph shows changing population statistics during the early part of the twentieth century. A line graph showing African American Population by Region, 1900 to 1930 comparing the Midwest to Northeast. X axis is years 1900, 1910, 1920, 1930. Y axis is Population in increments of 500,000 starting at 0 and ending at 1,500,000. In 1900 and 1910 both regions were around 500,000. In 1920 both grew to around 750,000, and in 1930 both were close to 1,250,000.

By the 1930s the African American population of the Midwest and Northeast

had more than tripled since 1900.
had more than doubled since 1900.
had increased by half since 1900.
had remained the same since 1900.

Had more than doubled since 1900.

Explanation:

The African-American population in the Midwest and Northeast was 500,000 people in 1900, and it gradually grew to 1,250,000 inhabitants by 1930. Therefore, to determine the percentage by which this population increased, the following mathematical calculation must be performed:

500,000 = 100

1,250,000 = X

1,250,000 x 100 / 500,000 = X

125,000,000 / 500,000 = X

250 = X

250/100 = 2.5

Thus, the Afro-American population in these regions multiplied by 2.5, that is, more than doubled during that period of time.

union blockade

explanation:

the union blockade in the american civil war was a naval strategy by the united states to prevent the confederacy from trading.

the blockade was proclaimed by president abraham lincoln in april 1861, and required the monitoring of 3,500 miles (5,600 km) of atlantic and gulf coastline, including 12 major ports, notably new orleans and mobile. those blockade runners fast enough to evade the union navy could only carry a small fraction of the supplies needed. they were operated largely by british citizens, making use of neutral ports such as havana, nassau and bermuda. the union commissioned around 500 ships, which destroyed or captured about 1,500 blockade runners over the course of the war.

the answer to your question is a. the salt plains

in 1811, he led an expedition, known as the george c. sibley expedition, to improve relations with the pawnee and kansa tribes, and also to locate the rumored jefferson's salt mountain