Why did the United States enter World War I?

Why this is the answer

The short answer USCIS lists first is that Germany attacked U.S. ships, including civilian ones. When war broke out in Europe in 1914, President Woodrow Wilson declared that the United States would stay neutral and asked Americans to remain impartial. That got harder every year. In May 1915 a German submarine attack on the Lusitania killed 128 Americans. Germany then promised to follow the traditional rules of search and seizure, but on February 1, 1917, it renewed unrestricted submarine warfare. The last push came from a coded message, the Zimmermann Telegram, in which Germany's foreign minister offered Mexico U.S. territory in return for joining the German side. British codebreakers had deciphered it, and when it appeared in the American press on March 1, public opinion turned hard against Germany. Wilson went to Congress on April 2, 1917, and said the world must be made safe for democracy. Congress declared war on April 6. The request had to go to Congress because the Constitution gives Congress, not the President, the power to declare war. The other two official answers describe sides rather than causes. Going in "to support the Allied Powers" means joining England, France, Italy and Russia. Going in "to oppose the Central Powers" means fighting Germany, Austria-Hungary, the Ottoman Empire and Bulgaria. Germany is the anchor in both: it attacked the ships, and it was one of the leaders of the Central Powers. A tempting wrong answer comes from the next war. Pearl Harbor explains why the country entered World War II, not World War I, and the two questions sit close together on the list. A simple way to separate them: the first war began for Americans at sea, with German submarines attacking ships; the second began with a Japanese attack on a naval base in Hawaii. Wilson, who asked Congress for that declaration, had won reelection in 1916 on the slogan "He kept us out of war," which shows how reluctant the country was before 1917.