Not surprisingly, the major reason that Russia sold Alaska to the United States was the fact that the Russian Tsar needed money.
Russia sold Alaska to the United States in 1867. The Tsar at the time was trying to modernize the country in a number of ways. One thing that was needed in order to modernize the country was money. Russia felt that selling Alaska was a good way to get some money, especially because they were not sure that they could hold on to the territory anyway. They had recently lost the Crimean War and were somewhat afraid that they might lose Alaska in another war with the British.
It is also said that Alaska no longer had much usefulness to Russia. The trade in sea otter fur was declining and there were very few Russians actually in Alaska.
So it seemed like a good idea to get rid of Alaska and Russia preferred to sell it to the US instead of selling it to Great Britain since Britain was more of an enemy of Russia than the US was.
USA purchased Alaska from Russia in 1867 for $7,200,000. The USA agreed to buy Alaska and Russia agreed to sell it primarly because the US evaluation of the value of Alaska at that time was higher than the agreed price, while that of Russia was lower than that of the purchase price. Besides at the time the transaction took place.
When the transaction took place, Alaska was a largely uninhabited waste territory, and many people thought that USA paid an exorbitant price for it. However, as the facts have turned out to be there is no doubt that USA profited substantially from purchase of Alaska.