U.S. State Fuel Octane Standards

Most states do not mandate certain standard gasoline grade octane ratings. In the United States and Canada, octane ratings are in AKI, commonly shown as "(R+M)/2". All states require gas pumps to be labeled with the correct octane level and nearly all states do regular testing to make sure gas stations are in compliance. A minimum 82 octane fuel is recommended for most vehicles produced since 1984. Older cars with carburetors could operate with lower octane fuel at higher elevations. Regardless of legality fuel with an octane rating of less than 82 is generally not offered for sale in most states. However 85 and 86 octane gasoline can still commonly be found in several rocky mountain states.

State Octane Ratings

The octane ratings below are the lowest allowed by law and may or may not reflect the actual levels offered for sale at most gas stations. Ethanol's effect on octane is not considered--these are ratings that are seen at the pump.

State	Regular Unleaded	Mid-Grade Unleaded	Premium Unleaded	Notes
Alabama	87	89	93
Alaska	87	89	90
Arizona	87	89	91
Arkansas	87	89	93
California	87	89	91
Colorado	85	87	91
Connecticut	87	89	93	86 octane may be sold if labeled as economy[1]
Delaware
Florida	87 [2]	89	93
Georgia	87 [3]	89	93 [4]
Hawaii	87	89	92
Idaho
Illinois	87 [5]	89	91	93 is available at Shell and some other gas stations in Illinois.
Indiana	87	89	93
Iowa	87	91	93
Kansas	87	89	91
Kentucky	86 [6]	89	91
Louisiana
Maine	87	89	91	93 (exclusively available where Shell V-Power Premium unleaded gas is sold)
Maryland	87	89	93
Massachusetts	87	89	93
Michigan	87	89	93	85 and 86 octane may be sold if labeled as subregular[7]
Minnesota		88 [8]	91
Mississippi
Missouri
Montana	85.5 [9]
Nebraska
Nevada
New Hampshire
New Jersey				New Jersey checks for fraudulent labeling of octane ratings.[10]
New Mexico	86	88	91
New York	87 [11]	89	93	93 is widely available.
North Carolina	87	89	93	91 octane is commonly sold as "premium" in the western, mountainous part of the state.
North Dakota	87 [12]	89	92
Ohio	87	89	93
Oklahoma
Oregon	87	89	92
Pennsylvania	87	89	93
Rhode Island	87	89	93
South Carolina	87	N/A	91	lower octane gas can be sold if labeled as "sub-standard" or "sub-regular"[13]
South Dakota	85/87	87/89	91	85 octane must be sold with a warning label displayed at the pump.[14] 85 and 86 octane can be sold as regular fuel only in the counties of Butte, Custer, Fall River, Harding, Lawrence, Meade, Oglala Lakota, Pennington, and Perkins.[15] 87 and 88 can be sold as mid-grade in the previously-named counties.[15]
Tennessee	87	89	91	93 widely available
Texas	87	89	93	El Paso area has 86/88/91 octane ratings
Utah	85	88	91
Vermont
Virginia	87	89	93
Washington	87	89	92
West Virginia	87	89	93
Wisconsin	87	89	91	93 widely available
Wyoming	85	88	91

References

1. http://www.ct.gov/dcp/lib/dcp/pdf/laws_and_regulations/motor_fuel_quality_regs_current_12042008_(2).pdf
2. Florida Administrative Code 5F-2
3. http://agr.georgia.gov/1fuel-measures-faqs.aspx
4. http://agr.georgia.gov/1fuel-measures-faqs.aspx
5. http://www.ilga.gov/legislation/ilcs/ilcs3.asp?ActID=2339
6. http://www.lrc.state.ky.us/kar/302/079/010.htm
7. https://www.legislature.mi.gov/(S(kvnx05fhsdtufphvy1a1ste3))/documents/mcl/pdf/mcl-Act-44-of-1984.pdf
8. https://www.revisor.leg.state.mn.us/statutes/?id=239.752
9. http://bsd.dli.mt.gov/weights-and-measures/faq
10. "New Jersey Weights and Measures" (PDF). NJ Department of Law and Public Safety. Retrieved 7 September 2017.
11. http://law.justia.com/codes/new-york/2012/agm/article-16/192-a
12. http://www.legis.nd.gov/information/acdata/pdf/33-34-01.pdf
13. http://www.scstatehouse.gov/code/t39c041.php
14. https://sdlegislature.gov/Statutes/Codified_Laws/DisplayStatute.aspx?Type=Statute&Statute=37-2-39
15. https://sdlegislature.gov/Statutes/Codified_Laws/DisplayStatute.aspx?Type=Statute&Statute=37-2-44