I am writing an application for which I would like to use the Geocoding API Reverse Address Lookup or any other geocoding method to get a list of states that are within a fixed radius from a specific lat long location. I am limiting this app to US addresses only. How would I best retrieve this information?
There is no need for reverse geocoding here. All you need is a list of states with their center points as lat/lon, and you check the distances between them and your location. If you are interested in exact lines of state boundaries and finding distances to the nearest points of state boundaries, you apply the same logic but to the points denoting the boundaries. State boundaries are available from many sources, e.g. US Census Bureau.