“I am a galley slave to pen and ink.”

What It Means to Be a Poet in America (1926)
Context: Whenever I begin to write a poem or draw a picture I am, in imagination, if not in reality, back in my room where I began to draw pen-and-ink pictures and write verses in my seventeenth year. Both windows of the room look down on the great Governor’s Yard of Illinois. This yard is a square block, a beautiful park. Our house is on so high a hill I can always look down upon the governor. Among my very earliest memories are those of seeing old Governor Oglesby leaning on his cane, marching about, calling his children about him.

Quoted by Bishop Jean-Pierre Camus in The Spirit of Saint Francis de Sales, ch. 7, sct. 3 (1952)

Source: The Count of Monte Cristo

My Address, written in Military Prisons of Bogiati, 5 June 1971 – After beating.
Poetry, Vi scrivo da un carcere in Grecia (I write you from a prison in Greece) (1974)

Ballads of a Bohemian (1921), It is later than you think http://plagiarist.com/poetry/4052/

Source: Story People: Selected Stories & Drawings of Brian Andreas

The Dryness and the Rain.
Brother, Sister (2006)

Not a Kerouac quote, but part of the text from a publicity campaign for the Beat Museum, San Francisco, composed by the advertising agency Gyro: http://paulacw.com/The-Beat-Museum
Misattributed

"What Has Become"
For Whom The Troubadour Sings (2010)