A primary source would be an eye witness account of the event. Someone who seen it happen.
The establishment of electric utilities led to widespread use of electricity in the United States.
<u>Explanation:</u>
Electricity was not used only to power homes but also factories and industries. This eventually enabled factories and industries to make use of large and sophisticated machines that could help in increasing the efficiency and productivity of the factories.
This enhanced the industrial revolution which was already taking place in the United States.With electricity, workdays and work time increased which led to increased production and thereby led to the boost in the economy of the United States.
Zheng He's first voyage (1405-1407) began in July 1405. They set sail from Liujiagan Port in Taicang of Jiangsu Province and headed westward. The fleet had about 208 vessels total, including 62 Treasure Ships, and more than 27,800 crewman. They traveled to present day Vietnam.
The iron curtain refers to the Berlin Wall which separated Europe during the Cold War. This term symbolizes the efforts by the Soviets to block itself from the West.