The capitalization of states is an easy rule to remember. The names of each state represent specific places and must be capitalized. However, there are a few other grammar rules to be aware of when it comes to writing the names of states.
Because state names represent specific places, they are always capitalized. If they are paired with a specific city, the first letter of the city's name will also be capitalized. A comma should come between a city and state to properly punctuate it. For example:
While state names are often shortened to their two letter abbreviation when addressing an envelope or writing an inside address, a state name used in writing should always be written out completely.
For example, the two letter abbreviation for New Jersey is NJ; it is rarely seen in writing in that form except for mailing purposes.
Some state names have a direction attached to them, such as North Dakota and South Dakota. In general, directions such as north, south, east and west are not capitalized. However, because the direction is part of the state name in some state names such as South Dakota, the direction must be capitalized.
When using the word "states" or "the States" in writing, the capitalization of states will depend on the meaning and intended usage. If the writer is referring to the United States and calling it just the States, then states needs to be capitalized. If states is being referred to in a general manner, such as "There are two senators for each state," then the word states would remain lower case.