What is the calorie intake for the average American?
United Nations FAO says the average American consumes 3770 calories for 2001-2003.
This number is much greater than many other sources, for example the American Cancer Society, which lists it (as of 2000) at 2618 for men and 1877 for women.
The reason the United Nations FAO number is higher is because it includes not just the calories Americans are eating but also the calories wasted to "spoilage, plate waste, and cooking". See the USDA Agriculture Factbook.
On average for a moderately active male aged between 14 and 28 their calorie intake for an average day should be between 2400 and 2800 for a moderately active female aged between those ages, it should be around 2000. This is by no means something you should stick firmly to, as calorie intake differs from person to person.