The answer is 'Railroads'
The Industrial Revolution in England lead to the development of trains and fast travel.
The United States quickly adopted the technology and brought in English businessmen and engineers to develop railroads in it's sprawling western states.
Railroads were integral in the early years in to cement newly acquired states under the control of the Federal government.
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The Persian ruler Darius l promoted the religion Zoroastrianism.
It was the <span>departure of the Allied Nation of "Russia" in late 1917 was a turning point in the war, since Russia withdrew from the war due to an internal revolution, which brought about a new era of communism. </span>
