use an atlas or google to get the area of the US including Alaska and Hawaii, they will likely give you an area in square miles... you will need to convert this...
get a dollar bill and measure its length and width in inches, multiply these dimensions to get the area...
now...remembering there are 5280 feet/mile and 12 inches per foot, there are 5280x12=63,360 inches per mile
BUT, in a square mile, there are 63,360² square inches, or 4.014x10^9 square inches in a mile...
So, take the area of the US, multiply by this number and you have the total area of the US in square inches
divide this number by the area of a dollar bill, and that is the number of dollar bills you need
divide this number by 300,000,000 or 3x10^8 (the population of the US) to get the number of dollars per person
ok, I checked the CIA factbook...the total land area of the US (incl. Hawaii and Alaska) is 2.37x10^7 sq mi (I converted from square km to sq mi), this means there are 9.53x10^16 sq inches in the US
the dollar bill is 2.61" by 6.14" for an area of 16 square inches
this means you need 9.53x10^15 dollars to cover the US!!
dividing by each person in the US, you would need 3.18x10^7 dollars per person, or 31million dollars...so...not something that is likely to happen