Should the word counties be capitalized in Nassau and Suffolk counties?

The word "counties" should not be capitalized when referring to Nassau and Suffolk counties.

Here's why:

* Proper Nouns vs. Common Nouns: "Nassau" and "Suffolk" are proper nouns (specific names) and should be capitalized. "Counties" is a common noun (general term) and should remain lowercase.

* Consistency: Following this rule ensures consistency in how we refer to geographical entities. We would similarly write "Los Angeles County," "King County," etc.

Therefore, the correct way to write it is: Nassau and Suffolk counties.