Usually, state geocoins are designed and produced by geocachers associations from each state.
Also, usually these coins have a Custom Code Prefix, the abbreviation of the state they represent. (IA Iowa, WA Washington, etc...) The first state coins were those of Texas (2002), Oregon and Kentucky (2003), the last was South Dakota (year 2012). The first state coins had some similarities to each other. For example, Texas 2003, Oregon 2003/2004, California 2004 (as the USA 2003), are the only ones with the official logo on the back.