List of the largest optical telescopes in North America

This is a list of the largest optical telescopes in North America.

21st century

A list of optical telescopes located in North America by aperture.

Some of the big traditional refracting lens telescopes in North America:

Name/Observatory	Location	Lens diameter	Focal length	Built	Comments	Image
Yerkes Observatory	Williams Bay, Wisconsin, USA	102 cm	19.4 m	1897	Largest in operation
James Lick telescope Lick Observatory	Mount Hamilton, California, USA	91 cm	17.6 m	1888
William Thaw Telescope Allegheny Observatory	Pittsburgh, Pennsylvania, USA	76 cm	14.1 m	1914	Brashear made, photographic
Leander McCormick Observatory	Charlottesville, Virginia, USA	66 cm	9.9 m	1884	completed c. 1874, installed 1884
U.S. Naval Observatory	Foggy Bottom Washington, DC, USA moved to Northwest, Washington, D.C., 1893	66 cm	9.9 m	1873	Largest refractor in 1873. Alvan Clark & Sons mounting replaced with Warner & Swasey mounting in 1893.
Sproul Observatory	Pennsylvania, USA	61 cm	11.0 m	1911	Currently under restoration to be re-installed in Northwest Arkansas
Lowell Observatory	Arizona, USA	61 cm	9.75 m	1894	Alvan Clark & Sons telescope

Optical telescopes only

Name /
Observatory

Image
Out

Image
In

Aperture

First
Light

Nation

200 inch
508 cm

1949

Some of the largest at observatories:

Name/Observatory	Aperture cm	Type	Location then	Extant*
Harvard Great Refractor, Harvard College Observatory	38 cm	achromat	Cambridge, Massachusetts, USA	1847
Merz und Mahler, Cincinnati Observatory	28 cm	achromat	Cincinnati, Ohio, USA	1843
West Point Observatory 9.75 inch Fitz equatorial	24.77 cm	achromat	West Point, USA	1839
Fraunhofer Refractor, United States Naval Observatory	24.4 cm	achromat	Foggy Bottom, D.C., USA	1844
Wesleyan University 6-inch Lerebours refractor	15.24 cm	achromat	Connecticut, USA	1836
Yale Dollond 5-inch, Yale College Observatory	12.7 cm	achromat	New Haven, Connecticut, USA	1828
Utzschneider & Fraunhofer Comet Seeker	10.2 cm	acrhomat	Foggy Bottom, D.C., USA	1843