Why did the US become involved in WW Ii and who was the president at the time?

Woodrow Wilson was the president before and after the US entered WW I. The main reason for the US involvement was that German U-boats sank several US ships and other passenger ships that were carrying American passengers. THe US felt a natural kinship with Britain due to the large number of Americans with British ancestry and with France due to French aid in the American Revolution. The last straw was learning that Germany was negotiating to form an alliance with an anti-US faction that was contending for control of Mexico.