If you have a math brain you will quickly see that the answer is: a little over a hundredth of a square mile per person (307 million people divided into nearly 3.8 million square miles).
The precise answer is 0.0123585765472313 square miles per person. Which doesn't sound like very much ... until you convert it to square feet. That 1.2~% of a square mile converts to a few inches less than 37,847 square feet!
Think of it this way: If you live in a 2,000-square foot home (fairly roomy for a family of 4, at least by most people's standards), you could fit nearly 19 such homes in "your space." Though no room would be left over for a yard ...
For some people, particularly those raised on farms, it might be easier to think of this in terms of acreage. In our town, five-acre plots were once the norm, though this has since come down in size quite substantially. Our 2,000-square-foot home sits on five-eighths of an acre, which feels quite roomy to us. (And much of our property is actually covered with forest.)
An acre is 43,560 square feet. Therefore your 37,847 square feet of land converts to just shy of an acre (about 87% of an acre). Comfy, eh?
Of course most of the 3.8 million square miles of land in the U.S.A. is private land which you do not actually own. (And very few of us actually own an acre of land!)
Also, according to the Natural Resources Council of Maine, state and federal governments own 34.71% of all land in the United States. (I assume that additional land is owned by local governments, such as city and county governments, but I'm not sure how much.) But much of this land is actually accessible to us as citizens as recreational land. In fact, federal and state governments will tell you that they hold such land "in trust" for we mere citizens.
My next question is, in terms of space, how do we here in the U.S.A. compare to people in other countries? Here's what my research turned up, from most spacious to least spacious:
|Russia||141,419 sq. ft. per person|
|Bangladesh||1,145 sq. ft. per person|
It's amazing to think that Bangladesh has 123-1/2 times the number of people crammed into its land mass as one of its neighbors to the North, the Russian Federation!
And that Russia has almost four times the square footage per person than we do here in the U.S.!
And that we have more than 10 times the amount of space per person than Haiti does.
Also, the global average (if you take all of the 7.1+ billion people on the planet, and divide this into earth's total land mass, you come up with an average of 24,785 square feet per person on the planet -- a full third less than what we live with here in the U.S.
Also should note that when the world's population doubles to more than 14 billion (about 2100? Experts disagree on the answer to this question), the average square footage per person will drop to about that currently enjoyed by Costa Rica's residents. (But we will still have four times the space they currently have in India!)
So ... do you feel like you have enough space in your life? Need more? What would you do with it if you had it?