Statistics for occurrence #1 of “Chicago” in chapter 13 of Thomas Wentworth Higginson, Henry Walcott Boynton, Reader's History of American Literature:
...on's .
1880. Cable's .
1882. Longfellow and Emerson died.
1884. Mark Twain's .
1885. Howells's .
1891. Lowell died.
1892. Whittier and Whitman died.
1893. World's Fair at Chicago .
1894. Holmes died.
1898. Spanish-American War.
1901. Theodore Roosevelt, President.
1902. Bret Harte died.
...