How does the first person narration in On the Road affect the novel?
Ah! Good ol' Jack Kerouac! He was one of the most popular Beatniks of the time period. On the Road was instrumental for popularizing the run-on sentence! What I mean by that is that the Beats believed in the value of a stream of consciousness when writing. I remember my professor saying over and over again when we were learning this book, "First thought; best thought." And don't we usually think in the first person tense?
Kerouac uses first person tense because he is the observer and the first-hand account witness of the goings-on that he describes. So the first person structure helps him to write whatever comes to his brain at the moment that he thinks about it; believing the whole time that raw language and thoughts could bring about a counsciousness of self not otherwise found in structure, or grammar, or rules of writing.