What ever happened to the Presidents?

Working closely with the schools in my area I always ask the same question year after year. Every year for a month my kid has to learn about MLK and black history but yet the rest of the year there is minimal time spent on learning Presidents ,Capitols and other curriculum needed to get into college. Why is so much time spent on such a brief point in history and what do we really gain by it? Shouldn't other cultures and historic figures be studied with the same enthusiasm?