Why do people want to cross the border in book called Lupita Manana?

It seems like you're referring to the book "Lupita Mañana" by Patricia Beatty. However, there's no mention of people wanting to cross a border in the story. The novel is about a young girl named Lupita who lives in a small Mexican village and dreams of a better life for herself and her family.

Can you clarify your question? Perhaps you are thinking of a different book or have misremembered something from the plot.