Answer: Expanding the territory of the United States and giving American traders access to the northern rim of the Pacific
Step-by-step explanation:
With the Crimean War having ended, Russia realized that Alaska was quite vulnerable to British invasion and acquisition from Canada and so sought to sell it to free themselves of the burden of having to defend it.
They approached U.S. Secretary of State William Seward who began the acquisition process after the American Civil War.
In acquiring the territory in 1867, America was able to increase it's land mass significantly as well as giving American traders a foothold in the North to enable them trade in Asia and the northern Pacific.