A method for identifying a merchant debit routing table includes: storing a plurality of transaction data entries, each entry including a first and second debit network, a utilized network, a merchant identifier, and a transaction date, the utilized network being the first or second debit network; receiving a routing identification request, the request including a merchant identification; identifying a merchant transaction group, the group including entries where the merchant identifier corresponds to the merchant identification; identifying a plurality of network subgroups in the group, each subgroup including entries including a common first and second debit network; identifying, for each subgroup, a preferred network based on the utilized network for each entry in the subgroup where the transaction date is a specific date; and identifying a routing table for a merchant associated with the merchant identifier based on the preferred network and the first and second debit network for each subgroup.