As of 2015, no state quarter is more valuable than any other, as the majority of them are in circulation with a value of 25 cents. However, state quarters struck in error are more valuable to collectors due to their rarity.
Based on the number of quarters struck and current state census data, the rarest state quarter with respect to supply and demand is California, with only 520.4 million state quarters struck. Compared to California's current population of 36 million, the California quarter has a per capita rarity index of 14.4 quarters per resident. The remainder of the top five rarest state quarters are Texas, Florida, Illinois and Michigan.