20 Centavos

El Banco del Estado was the state bank of Sonora, one of several Mexican regional banks operating under the 1897 Ley General de Instituciones de Crédito, which granted concession rights to issue paper currency within defined territorial limits. The small denominations in this series — and 20 centavos is among the smallest — were printed to address the chronic shortage of small change that plagued northern Mexican commerce, where silver fractional coin was routinely hoarded or melted.

Pick S502 places this squarely in the Sonoran concession issues. Surviving examples at this denomination are genuinely scarce; low-value notes from provincial Mexican banks circulated hard and were rarely preserved.