Crude oil's global collapse is now expected to soon push the national average U.S. price for gasoline below $2 a gallon for the first time since early 2009.

Nationally, regular unleaded gasoline currently averages about $2.12 a gallon, down 46 cents from just four weeks ago and $1.01 cheaper than year ago levels.

Gas prices are also expected to fall more than previously forecast for the full year.  The cost savings is projected to slash the USA's gasoline bill from about $460.5 billion in 2014 to about $340 billion this year.

Nationally, gasoline prices were last below $2 a gallon on March 25, 2009.  Nearly half of the U.S. retail outlets now average sub-$2 gasoline.

How about this for gas price extremes:

Cheapest state for a gallon of gas:  Missouri at $1.76

Most expensive:  Hawaii at $3.42