Why were the prisoners sent to Patty's town in Summer of My German Soldier?
A small elaboration on the other respondence: Patty lives in a small town in the middle of nowhere in Arkansas, a place that likely had few if any German immigrants as part of its population. It also had plenty of open space available for field work--picking cotton. Thus, the German soldiers would have plenty of outside work to do and probably no one in the town would feel much sympathy for them, which could have been the case had they settled in a place near, for example, Cincinnati, which had/has a large German population, some of which might have had some sympathies for German pow's. Remember not all Germans were Nazis, which is an immportant point of the story.
There were prisoner-of-war camps all over the U.S. during World War II. When Japan attacked Pearl Harbor, the U.S. didn't think about prisoners of war, so when the numbers grew, they had to consider where to put them. Basically, they tended to put the prisoners in a state that had a similar climate to the home of the prisoners. Most of them were used as laborers in some capacity, depending upon where they were and what was needed.