Lincoln visited Buffalo on February 16, 1861 on his trip to accept the presidency of the United States. During his visit, he stayed at the American Hotel on Main Street between Eagle Street and Court Street. The Civil War years saw an increase in the population of Buffalo which grew from 81,029 to 94,210 by 1865. In addition to sending many soldiers to the Union effort, Buffalo manufacturers supplied important war material. For example, the Niagara Steam Forge Works manufactured turret parts for the ironclad ship USS Monitor.
Grover Cleveland served as Sheriff of Erie County (1871–1873), and was Mayor of Buffalo in 1882. He was later Governor of New York (1883–1885), 22nd President of the United States (1885–1889) and 24th President (1893–1897).
In May 1896, the Ellicott Square Building opened. For the next 16 years, it was the largest office building in the world. It was named after the surveyor Joseph Ellicott.
At the dawn of the 20th century, local mills were among the first to benefit from hydroelectric power generated via the Niagara River. The city got the nickname City of Light at this time due to the widespread electric lighting. In 1881, Buffalo deployed the first electric street lights in the United States. It was also part of the automobile revolution, hosting the brass era car builders Pierce Arrow and the Seven Little Buffaloes early in the century. City of Light (1999) was the title of Buffalo native Lauren Belfer's historical novel set in 1901, which in turn engendered a listing of real versus fictional persons and places featured in her pages.
President William McKinley was shot and mortally wounded at the Pan-American Exposition in Buffalo on September 6, 1901. He died in the city eight days later and Theodore Roosevelt was sworn in at the Wilcox Mansion as the 26th President of the United States.
An international bridge, known as the Peace Bridge, linking Buffalo to Fort Erie, Ontario was opened in 1927
