S.E. Hinton uses the motif of sunsets to create a connection between two unlikely characters, Ponyboy Curtis and Cherry Valance.  Although Ponyboy is a greaser and Cherry is a pretty, popular Soc and a cheerleader as school, both of the characters discover that they share a common interest--sunsets. 

When the two characters meet at the Drive-In, Cherry discovers that Ponyboy is really easy to talk to and confesses "I think you're the first person I've ever really gotten through to" (38).  In that same conversation, the popular Soc girl guesses that Ponyboy is the kind of boy who "likes to watch sunsets, too"  (40).  Ponyboy contemplates this and wonders about Cherry watching sunsets:

It seemed funny to me that the sunset she saw from her patio and the one I saw from the back steps was the same one.  Maybe the two different worlds we lived in weren't so different.  We saw the same sunset" (40-41).

Hinton establishes the sunset as an early motif for her larger theme in the novel, to look past stereotypes and see people are individuals; the end of the novel reinforces the sunset as a commonality for all of humanity as Ponyboy imagines "hundreds of boys who maybe watched sunsets and looked at stars and ached for something better" (179).