Ida Saxton married McKinley on January 25, 1871 at the First Presbyterian Church in Canton, Ohio. The McKinley's had two daughters, but their daughters died at a young age. His wife had seizures in public because of epilepsy.

He attended New York Law School after the war. He became a lawyer in Ohio in 1867. He was a U.S. Representative from 1877 to 1883 and from 1885 to 1891. McKinley was also governor of Ohio from 1892 to 1896.

He won his first election during the campaign of 1896, when he was running against William Jennings Bryan. McKinley was part of the Republican Party.

On February 15, 1898, the U.S. battleship Maine was sunk in Havana, Cuba. Because of this, the U.S. declared war on Spain. McKinley led the way to victory as the U.S. pummeled the Spanish Army. The war took less than four months but more people died from disease than were killed in battle. During the war, the Americans gained possession of Guam, the Philippines, Cuba and Puerto Rico. 

As President there were great changes that he made. McKinley passed a law called the McKinley Tariff, which helped raise money for the government. He raised the taxes by a bit to save some money for other businesses. He also had a policy called the Open Door Policy so China would have equal trading rights.

He won his second term in office during the 1900 campaign by defeating William Jennings Bryan for the second time. He had 7,219,828 and Bryan had 6,358,160 popular votes. Bryan had 144 electoral votes compared to McKinley's 292. He chose Theodore Roosevelt as his running mate. 

Just before the start of his second term something bad happened. He went to Buffalo, New York to give a speech at the Pan-American Exposition and was shot twice by Leon Czologz, an anarchist. The bullet was buried so deep that the doctors couldn't find it. He died on September 14, 1901 because of the disease gangrene. Theodore Roosevelt took charge as President on the same day McKinley died.