Blakelock perhaps received some artistic instruction in his youth from his uncle James A. Johnson. He entered the Free Academy of the City of New York (now City College) in 1864, which he left in 1866 to begin painting. Blakelock first exhibited at the National Academy in 1868, showing frequently through 1899. He began his close friendship with the artist and active Academy member, Harry M. Watrous, around this time. Watrous was to provide Blakelock with importrant critical and financial support throughout their friendship.
Blakelock's only extensive traveling was during the years from 1869 to 1871, when he appears to have visited Kansas, Colorado, Wyoming, Utah, Nevada, California, Mexico, Panama and Jamaica. This trip had an lasting impact on the subject themes of his paintings, for Blakelock frequently depicted western landscapes and scenes of Indian life. In 1877 in New York, Blakelock married Cora Rebecca Bailey, whom he had known from childhood summers spent in Vermont.
The ensuing years were tragic for Blakelock. In the 1880s, he received some patronage for his Barbizon-influenced nocturnes which features moonlit woodlands with lacy foliage set against the night sky or romantic, dark seacapes. But his work was too individualistic--the result of his personal vision and laborious techniques, which built the paint in layer upon layer--to gain wide favor.
Increasingly plagued by the financial pressures of supporting his large family, Blakelock suffered his first nervous breakdown in 1891 and was briefly hospitalized. However, his behavior became increasingly eccentric. In 1899 he was admitted to the Long Island Hospital at Kings Park, New York, and three years later was transferred to Middletown State Hospital for the Insane, where he remained until 1916. He continued to be periodically confined during the remaining three years of his life. Blakelock died while resident at the home of a Mrs. Van Rensselaer Adams, who had taken over management of his affairs in his last years. Blakelock's visionary, melancholic landscapes went largely unrecognized until the early twentieth century, becoming increasingly respected over the course of time.
The eulogy entered into the minutes of the Academy's annual meeting, April 20, 1920, described him as a "gifted painter" and noted "the strange beauty of color and design in many of his landscapes. His moonlit scenes, in particular, are flooded with that mysterious 'light that was never on sea or land'," and particularly lamented that "wide-spread recognition of his genius did not come to him until after his reason became clouded."
