The Library says:
Written over a period of three weeks in April 1951 in manic bursts of what Allen Ginsberg referred to as ‘spontaneous bop prosody’, Jack Kerouac typed the manuscript on rolls of tracing paper, which he taped together into a long scroll to avoid replacing paper at the end of the page and interrupting his creative flow.
As the tale itself, I believe, tends to the serial (ashamed to say I have not read it), the scroll is a nice model of that temporal linearity.We are delighted to welcome the 120-foot-long scroll to London for the first time. It will be on display in a specially-constructed case, alongside sound and printed materials from the Library’s collection.
According to Wikipedia, the scroll was bought in 2001 by Jim Irsay (Indianapolis Colts football team owner) for 2.43 million US dollars.
On the Road: Jack Kerouac's manuscript scroll is open until Thursday 27 December 2012.
Information on the British Library site.