The themes of American History by Judith Ortiz Cofer are cultural isolation and the effects of racism and xenophobia, signified in Elena's difficulty living in Patterson, New Jersey and how the attitudes of people around her affect her feelings about herself and the world.
Elena -- also known as Skinny Bones -- experiences a lot of negative interactions with people due to their racism and xenophobia. For example, a girl at the beginning of the story yells at Elena for not jumping rope fast enough, saying "Didn't you eat your rice and beans and pork chops for breakfast today?" The other girls start making up a chant with the word pork chop and Elena feels embarrassed and upset.
She thinks about how difficult it is to live in a city in winter. Elena hates the weather and how the black girls in her class seem to always be warm and fast, while she's cold and slow. She envies them. She fantasizes about life in Puerto Rico, where she's only been once. She says that the stories her parents tell about it are like fairy tales.
Elena is blocked from advanced classes -- despite her excellent grades -- only because English is not her first language.
Her relationship with Eugene isn't marked by the racism and xenophobia that mar many of her other encounters. However, when she visits his house, his mother immediately dismisses her and sends her away. She tells Elena that Eugene cannot study with her based only on Elena's looks and where she lives.
Elena's reaction to the death of President Kennedy shows her isolation from other people. They're all very affected and her mother asks Elena to go to church with her. She also expresses surprise that Elena is going to see Eugene now that President Kennedy is dead. Elena, on the other hand, goes home from her encounter with Eugene's mother shocked and tries to feel sad for President Kennedy. She is only able to find tears for herself in the end.