During World War 1 why didn't the US join the war after the Lusitania was sunk?

The sinking of the Lusitania in 1915 heightened anti-German sentiment in the U.S. but did not immediately lead to American entry into World War I. President Woodrow Wilson preferred a policy of neutrality and sought to mediate peace rather than engage in conflict. Additionally, strong economic ties to the Allies and a divided public opinion contributed to the reluctance to join the war until factors like unrestricted submarine warfare and the Zimmermann Telegram in 1917 ultimately shifted American sentiment towards intervention.