According to the U.S. Postal Service, the proper abbreviation for "circle" in addresses is "CIR." Although "CIRC," "CIRCL," "CRCL" and "CRCLE" are commonly used, "CIR" is the standardized abbreviation preferred for all mail.
The U.S. Postal Service recommends that proper, standardized abbreviations be used on all mail. Mail processing is increasingly automated, and standardized abbreviations and address formats allow for quicker processing speeds with fewer mistakes. Other lesser-known abbreviations include "BR" for "branch," "CMN" for "common," "GDN" for garden and "LGTS" for lights. The Postal Service also recommends that all components of addresses are written in simple, block-style capital letters with no more than two spaces between any component.