Aggregate state and local effective tax rates on businesses are calculated for each of 48 continental states in this research. The calculation is done by adding up all taxes that businesses are legally liable for, and dividing by either net business income or the value of the business capital stock. While the research does not draw any conclusions about tax burdens or incidence, it shows clearly that: state and local taxes have become a significant share of business income (average 8%), and show a very wide variation across states (4%-12%). The results should prove useful to those trying to study the incidence of such taxes, and their effects on business resource allocation.