Flags

American Goldfinch was created in 1758.

American Pastime was created in 1976-03.

American Laser Skincare was created in 2002.

Central American Airways was created in 2008.

Three Flags was created in 1958.

American Songwriter was created in 1984.

American Guerrilla in the Philippines was created on 1950-11-08.

American Motorcyclist was created in 1947.

The American School of Marrakech was created in 1995.

American Capitalism was created in 1952.

Flag of Montserrat was created in 1909.

American Association of Woodturners was created in 1986.

American Notes was created on 1842-10-19.

American Megatrends was created in 1985.

American Look was created in 1969.

The Coming American Renaissance was created in 1996.

The American Scene was created on 30-01-19.

Flag of Syria was created in 1980.

Flag of Middlesex was created in 1909.

American Leak Detection was created in 1974.

American Decency Association was created in 1999.

American badger was created in 1778.

Chile's flag features blue, white, and red colors, symbolizing various aspects of the nation's identity. The blue represents the sky and the Pacific Ocean, the white symbolizes the snow-covered Andes Mountains, and the red stands for the blood shed by those who fought for Chile's independence. The white star in the blue square also signifies a guide to progress and honor for the country.

There are a lot of flags with the two blue bars and the white in the middle, San Salvador, Honduras, and Nicaragua are a few.

"A mailbox" fits. I don't know if it's what the person who invented the riddle had in mind or not.