What states require smog checks? Quick Answer
- As of 2025, 28 states and the District of Columbia require smog checks in certain areas, including California, New York, Texas, and Illinois. Smog tests are typically mandatory in high-pollution regions. Meanwhile, 22 states—like Florida, South Dakota, and Alabama—do not require emissions testing.
What Is a Smog Check?
A smog check is a test that measures how much pollution your car emits. If you're asking what is a smog check, it’s a state-required inspection aimed at reducing harmful emissions that affect public health and the environment. These checks often include inspecting your car’s tailpipe, emissions system, and onboard diagnostics. Depending on where you live, you might need one every year or two, especially if your car is older or diesel-powered.
What States Require Smog Test?
Based on the most recent data, 28 U.S. states and the District of Columbia require emissions testing in at least some areas. These states include:
| State | Source |
|---|---|
| Arizona | Arizona Department of Transportation¹ |
| California | State of California DMW² |
| Colorado | Colorado General Assembly³ |
| Connecticut | Connecticut DOT⁴ |
| Delaware | DNREC⁵ |
| District of Columbia | DC DMV⁶ |
| Georgia | Georgia’s Clean Air Force⁷ |
| Illinois | Illinois Environmental Protection Agency⁸ |
| Indiana | Indiana Bureau of Motor Vehicles⁹ |
| Louisiana | Louisiana Department of Environmental Quality¹⁰ |
| Maine | Maine Department of Environmental Protection¹¹ |
| Maryland | Maryland DMV¹² |
| Massachusetts | Commonwealth of Massachusetts¹³ |
| Missouri | Gateway Vehicle Inspection Program¹⁴ |
| Nevada | Nevada DMV¹⁵ |
| New Hampshire | New Hampshire DMV¹⁶ |
| New Jersey | New Jersey MVC¹⁷ |
| New Mexico | New Mexico MVD¹⁸ |
| New York | New York DMV¹⁹ |
| North Carolina | North Carolina DMV²⁰ |
| Ohio | Ohio Environmental Protection Agency²¹ |
| Oregon | Oregon DEQ²² |
| Pennsylvania | Commonwealth of Pennsylvania²³ |
| Rhode Island | Rhode Island DMV²⁴ |
| Texas | Texas Department of Public Safety²⁵ |
| Utah | Utah DMV²⁶ |
| Vermont | Vermont DEC²⁷ |
| Virginia | Virginia DMV²⁸ |
| Wisconsin | Wisconsin DMV²⁹ |
Sources: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29
These states may not test every vehicle or in every county, but residents in larger cities or high-pollution areas are usually required to get regular checks.
What States Don't Require Smog?
If you're wondering what states don't require smog, you're in luck if you live in one of 22 states that currently don’t mandate any emissions testing. These include:
| State | State | State |
|---|---|---|
| Alabama | Kentucky | Oklahoma |
| Alaska | Michigan | South Carolina |
| Arkansas | Minnesota | South Dakota |
| Florida | Mississippi | Tennessee |
| Hawaii | Montana | Washington |
| Idaho | Nebraska | West Virginia |
| Iowa | North Dakota | Wyoming |
| Kansas |
In these states, you can register your car and drive without a smog check—unless local city or county ordinances say otherwise.
Why Smog Checks Matter
Even if your state doesn’t require one, smog checks serve an important role. They help catch engine or exhaust problems early, protect the environment, and keep your car running efficiently. If you’re selling your car or moving, knowing what states require a smog test can save you time and fines.
Final Thoughts
Understanding what states require smog checks is key if you're relocating or buying a vehicle across state lines. Rules vary widely, and failing to meet your state’s requirements can lead to registration issues or penalties. If you live in a state that requires smog tests, stay on top of your testing schedule to keep your vehicle road-legal and environmentally friendly. And if you're in a no-test state, you’re off the hook—but it’s still smart to keep your car in clean running condition.
