By 1819 he had moved to New York City, where he sought to establish himself as a journalist and poet, but scraped by in varying degrees of poverty.

His character was described as "innocent as a child", imbued with a mystic romanticism,[5] and by common consent, he had no vices, but always preserved a gentility of deportment,[3] was inoffensive, and always mild, always happy.

Later he relied on the sale of poems to newspapers, journals and magazines, but was rarely able to keep a roof over his head, and in a letter to the New York Evening Post was described as "a poetic scintillator of some what odd fancies, who kept the town laughing while he was sometimes starving.

A policeman had found him in a destitute and apparently demented condition on the street and taken him to a jail for safety; but this triggered a mental collapse which saw him removed to an asylum.

[3] The immediate catalyst for the mental chain of incidents which brought about his death was the culmination of a cruel prank played on him by a group of youths, who elaborately convinced him that a certain woman for whom he longed was in love with him, before letting him down in the most abrupt fashion.

He was celebrated in life in an amusing poem called "The Discarded," written by Halleck, but it was upon Walt Whitman that he made the greatest impression.

No great compliment to the greatest Poet in America should like the change tho'; had to pawn my Diamond Ring (the gift of a lady), and go tick at Delmonico's for Dinner.

The greatest Poet of the Country ought to have the freedom of the City, the girls of the gentry gratis, grab all along shore, the magnificent Mary, and snucks with all the sweet Sisters of Song.

"Higgins states that Clarke's impact on Whitman was quite significant, influencing his choice of theme, persona as an outsider artist, and even in the incorporation of prefaces to his poetry collections.