The branches are Canal Winchester, Driving Park, Dublin, Franklinton, Gahanna, Hilliard, Hilltop, Karl Road, Linden, Livingston, Marion-Franklin, Martin Luther King, New Albany, Northern Lights, Northside, Parsons, Reynoldsburg, Shepard, South High, Southeast, Whetstone, and Whitehall.

On January 1, 1872, John J. Janney introduced an ordinance to the Columbus City Council which would allocate public funds for the construction of a library.

Columbus was initially passed over by Carnegie for funds to build a large main library, as it was against his preference for smaller branches accessible to local working class residents.

[10] Carnegie's secretary composed a letter stating that, “not more than one hundred and fifty thousand dollars would be spent upon the main building,” on the condition that the city fund the library for, “at least twenty thousand dollars a year.” The City Council approved the offer and used the initial funds to purchase the $40,000 estate of Thomas Ewing Miller at 96 S. Grant Avenue.

With cost of construction exceeding initial estimates, Carnegie agreed to fund an additional $50,000, bringing his full donation to $200,000.

A construction contract was awarded to James Westwater & Company, and the building was ready for occupancy in the fall of 1906.

[8][11] The building had a cost of $310,000; the city covered the remaining amount and agreed to pay at least $20,000 per year in maintenance and growth; a stipulation of Carnegie's gift.

Additional branches included Linden, Northside, Franklinton, Hilltop, Whitehall, Eastside, Beechwold, Parsons, Northern Lights, Hilliard, Livingston, Reynoldsburg, Bolivar Arms, Morse Road, Gahanna, Clintonville, Martin Luther King, Dublin, South High, Driving Park, House of Knowledge, Channingway, Hilltonia, and Shepard, opened between 1935 and 1980.

[13] Since it initially opened, the Main Library has undergone four major renovations and expansions to accommodate the city's increasing population, in the 1950s, 1961, 1990–1991, and 2015–2016.

[15] The Columbus Metropolitan Library (CML) system aims to inspire reading, share resources and connect people through their numerous programs and activities.

Since that time, CML has been listed within the top four libraries for its population size every year (note: no rankings were published in 2003 or 2007; Hennen ceased to produce this content after 2010).