When you visit the US, you would be stumped to know there are no ground floors anywhere. This can be confusing at the minimum and may leave you wondering what really happened to the ground floor, as you meander through maps to reach your destination.
A tourist can have a harrowing time figuring this out. It turns out that the reason for missing ground floors has nothing to do with the building planning or the quirk of the Americans. Rather, the answer lies in the way Americans understand what a floor means more than the rest of us.
In American English, the floor at the street level is commonly referred to as the first floor. You're on the second floor after going up one story (which, of course, is the first floor for the British). The basement, as in British English, refers to the floor below street level.
The ground floor of a building is referred to as such in British English. The floor above it is known as the first floor, while the floor below it is known as the basement. Since we inherited the English language from the British, the same nomenclature is followed here in India.
Things of course are changing in America too. Many public buildings in the United States refer to their street-level floor as the ground floors, as is done in the United Kingdom.