Having spent a considerable amount of time in Belgium, I know that there is fierce enmity between the Flemish and Walloon.
I think that we in the US should take this centuries long example to heart. In Brussels, where being bilingual is required to get a job, there is less fighting between the people.
Political inertia aside, how amazing would it be if the entire western hemisphere (save Brazil and Quebec) could communicate with each other easily? I think that the conservatives in every country would see that they aren't too different from each other. Lets make English and Spanish the coequal national languages of the USA.