Design a set of four stamps for the United States Postal Service (USPS). Limited to featuring American or American-related subjects that had a significant impact on American history, culture, or environment, the subject matter can be a person, place or thing, but, if people are selected, they cannot be living at present time and if they are no longer with us, they must be deceased for at least three years. No topic select ion that has negative occurrences, disasters, religious institutions, or religious leaders.