Pounds of CO2 per Square Foot of Road per Year Calculation: There are about 15,000 square miles of paved roads in the U. S. (the roads are long and skinny, but if you took roads and made them into a giant tennis court, you’d have about 15,000 square miles), or about 15,000 x 5280 x 5280 = 420,000,000,000 square feet (rounding off just a bit). For this answer, then, simply divide the answer from the previous question (number of pounds of CO2 per year produced by U. S. cars) by the total highway square footage number above. Cheap calculators? You likely won’t be able to type in the number of square feet; in that case, if you calculated a number of tons (T) in the previous question, you should do T x 2000 / 15,000 / 5280 / 5280, giving an answer very near to: