Which number president was William McKinley?

Under which president did Levi P. Morton serve as Vice President? Who was First Lady during Benjamin Harrison's presidency? Caroline Harrison was married to which president? Under which president did Adlai Stevenson I serve as Vice President? Who succeeded William McKinley as President of the United States? Which political party did President William McKinley belong to? Which president served from 1897 to 1901? In what year did William McKinley first take office as President?