A new fact sheet from the Institute on Taxation and Economic Policy indicates Iowa is one of seven states where the gas tax rates are “stuck in neutral.” According to the institute’s analysis, 21 states have gone a decade or more without increasing their gas tax rates and 16 states have gone two decades or more. The group says a lack of action has resulted in a significant drop in purchasing power as the cost of construction and maintenance has increased. There are 18 states where gas tax rates automatically grow over time, according to the report. Other key findings indicate seven states -- Alaska, Virginia, Oklahoma, Iowa, Mississippi, South Carolina, and Tennessee – have not seen an increase in their gas tax rate since the 1980s or earlier. Among the 32 states levying a “fixed-rate” gas tax, the average amount of time gone by since the last gas tax increase is 17.2 years. Most states levying a “variable-rate” gas tax have seen their gas tax rates rise some time in the last 12 months. “A lot of the problems with our infrastructure can be traced back to outdated gas tax rates that haven’t kept pace with the cost of construction and maintenance,” said Carl Davis, a senior analyst at the Institute on Taxation and Economic Policy.