What is the two-letter postal abbreviation for North Carolina?

In what year did New York ratify the U.S. Constitution? What is the official nickname of New York? What is the state bird of New York? What is the state flower of New York? Which state uses the postal abbreviation "NC"? Raleigh is the capital of which state? What is the largest city in North Carolina by population? In what year did North Carolina ratify the U.S. Constitution?