Why did the U. S buy Alaska?

On March 30, 1867, Secretary of State William H. Seward agreed to purchase Alaska from Russia for $7.2 million. At the time, critics thought Seward was crazy and called the deal "Seward's folly." Seward was laughed at for his willingness to spend so much on "Seward's icebox" and Andrew Johnson's "polar bear garden." that is why he buys Alaska