A manual for writers of research papers, theses, and dissertations, 7th edition - Kate L. Turabian 2007
Geographical terms - Place-names
Abbreviations
Part III. Style 20 spelling
In text, always spell out and capitalize the names of countries, states, counties, provinces, territories, bodies of water, mountains, and the like (see 22.1.1). One exception is the former Union of Soviet Socialist Republics, commonly referred to as the former USSR.
Always spell out United States when using it as a noun. When using it as an adjective, you may either abbreviate it to U.S. or spell it out (for a more formal tone). By convention, it includes periods, even though it is an acronym.
She was ineligible for the presidency because she was not born in the United States.
His U.S. citizenship was revoked later that year.
In tables, figures, citations, and mailing addresses, abbreviate the names of U.S. states using the two-letter, no-period postal codes created by the U.S. Postal Service.
AK - Alaska
AL - Alabama
AR - Arkansas
AZ - Arizona
CA - California
CO - Colorado
CT - Connecticut
DC - District of Columbia
DE - Delaware
FL - Florida
GA - Georgia
HI - Hawaii
IA - Iowa
ID - Idaho
IL - Illinois
IN - Indiana
KS - Kansas
KY - Kentucky
LA - Louisiana
MA - Massachusetts
MD - Maryland
ME - Maine
MI - Michigan
MN - Minnesota
MO - Missouri
MS - Mississippi
MT - Montana
NC - North Carolina
ND - North Dakota
NE - Nebraska
NH - New Hampshire
NJ - New Jersey
NM - New Mexico
NV - Nevada
NY - New York
OH - Ohio
OK - Oklahoma
OR - Oregon
PA - Pennsylvania
RI - Rhode Island
SC - South Carolina
SD - South Dakota
TN - Tennessee
TX - Texas
UT - Utah
VA - Virginia
VT - Vermont
WA - Washington
WI - Wisconsin
WV - West Virginia
WY - Wyoming
You may also abbreviate the names of Canadian provinces and territories where state names would be abbreviated.
AB - Alberta
BC - British Columbia
MB - Manitoba
NB - New Brunswick
NL - Newfoundland and Labrador
NS - Nova Scotia
NT - Northwest Territories
NU - Nunavut
ON - Ontario
PE - Prince Edward Island
QC - Quebec
SK - Saskatchewan
YT - Yukon