@ Ms. Sue
It brings people together rather than driving them apart because nationalism is caring about their country and making sacrifices for it. If people care about their country it would unite them as a whole into representing their country and have pride in their country.
Is this a good one? can you correct some of my mistakes and add some?
Your answer is good. However, today we're often seeing ignorant people denying that anyone different from themselves is not an American. They need to be taught that Americans pride themselves on their immigrant backgrounds.
Many years ago when I was teaching 7th grade geography in rural Michigan, one of the students proudly announced he had ancestors from three continents -- Africa, Europe, and Asia. He is a true American.