On the back of a penny, why is the 'o' in "of" in "United States of America" in lower case?

Question

The 'F', however, is capitalized.

Answer 1

Of is a preposition.  Prepositions and articles are not capitalized, even in the titles of things (unless it's the first word).

The United States of America

The Book of the Dead

Happiness is a Warm Puppy

Answer 2

Looks to me like the ' f ' in 'of ' is smaller than the rest of the letters too.  Guess it's not an important enough word to be capitalized on a penny!