Someone might have mentioned this earlier in the thread (in which case I must be buzzed for repetition) but part of the brilliance of this song is that it doesn't rhyme. It's superb poetry and superb communication.
It's interesting that another song that doesn't rhyme is Paul Simon's 'America'. It's also a song about a burgeoning relationship combined with social/geographic observation.
In contrast/irony, the song "Nothing Rhymed" follows a strict rhyme scheme. It doesn't really elucidate much though.