Fly a black and white American flag with a thin line to support your local heroes. Choose the popular thin blue line American flag or a solid black flag with a colored stripe. There are nine thin line flags: blue, red, green, and six more colors to honor different public services. The most iconic of these, the thin blue line flag, represents the police who serve as the “thin line” between the public and danger. Other popular versions include the thin red line American flag for firefighters, while park rangers use a green stripe American flag. Black and white flags provide a high-contrast background to spotlight your support. Discover the symbolism behind all nine colors in our thin line flag FAQ.