Gas prices fall below $2/gallon in 13 states

The price of a gallon of gas has fallen below the $2 mark in 13 states across the country, according to the price tracker Gasbuddy.com.

Three states have stations selling gas for less than $1.90, but the deals can only be found at a small number of stations.

The nationwide average is $2.55 a gallon, the lowest price the country has seen since October 2009.