Given that the average per gallon tax (state + fed) is about 50 cents, the tax may become the majority of price.
http://www.api.org/Oil-and-Natural-Gas-Overview/Industry-Economics/Fuel-Taxes/Gasoline-Tax
Missouri taxes are low. And while prices below $1 a gallon may be a pipe dream, a year ago did anyone think it’d be below $2 any time soon