Conversation so far:
who signed the treaty to purchase alaska from russia
The Alaska Purchase was signed by President Andrew Johnson.
when did the alaska purchase occur
Alaska was formally transferred to the United States on October 18, 1867, through a treaty ratified by the United States Senate and signed by President Andrew Johnson.
how did the alaska purchase come about
In the aftermath of the Crimean War, Emperor Alexander II of Russia began exploring the possibility of selling Alaska, which would be difficult to defend from Britain.

Question: when did the united states get involved
Self-contained rewrite: when did the united states get involved with the alaska purchase