I have a map which has one data point per zip code. I would like to change those points to zip code polygons. Any ideas on how to go about it?
Unless you have the precise geometry of each polygon, there's no way to just change a point into a polygon of the size and shape of something complex like political boundaries.
What you could do, however, is download a polygon file of zip codes (try here) and do a join (spatial join if you don't have a common identifier, by attributes if you do) to transfer all attributes of your point file over to the polygon file.