Delaware Car Idling Laws: Highways Only

Q: Which Delaware law actually covers this?

21 Del. C. § 4182, “Unattended motor vehicle”, in the Delaware vehicle code. It is a theft provision rather than an environmental one, which is why a search for an idling law does not return it. The operative sentence is quoted on this page and links to the Delaware Code Online page it was read from.

Q: Does it matter whether the car was locked in Delaware?

Not to whether the section applies. Nothing in the Delaware section makes the offence depend on whether the car was locked or the key taken out, which separates it from the 9 states where that is exactly what it depends on. What 21 Del. C. § 4182 requires is set out in its own words above.

Q: Can you leave a car running in your own driveway in Delaware?

The Delaware chapter that carries this section applies to highways, and the sentence doing that is quoted on this page. A driveway is not what that sentence describes. What can still reach a car standing on private ground is a city ordinance, and those are set by the city rather than by the state.

Q: What does Delaware charge for it?

Delaware prints no penalty inside the section, which is the commoner pattern: a violation falls to the chapter's general penalty provision. 18 states of the 34 print one where a reader would find it. The states that do print one are collected on the national page with the wording each of them uses.

Q: How current is this?

Every line was read on September 23, 2026, off the state's own published code, and links back to the section it came from. Legislatures amend these between sessions and a repeal leaves the old text in circulation for years afterwards, so the link beside each quote is what governs on the day.

Prohibited

Leaving it running unattended

21 Del. C. § 4182

No

Whether the lock matters

9 states of the 34 are built on it

Highways

How far the chapter reaches

one of 20 confined to a road

By regulation

Separate idling limit

7 DE Admin. Code 1145, Excessive Idling of Heavy Duty Vehicles

September 23, 2026

Read

off the state’s own code

The short answer

Delaware prohibits it, and the chapter reaches highways only.

Delaware prohibits it, but the chapter the section sits in applies to highways and not elsewhere. So the section and its reach are two separate readings: the prohibition is in one place and the sentence that confines it to highways is in another, and 20 states are built that way. Both are set out below in their own words.

A reader looking at the section alone would not see this. What confines it to a highway sits in the scope provision at the front of the chapter, reproduced below, and 20 states put it there.

Highways21 Del. C. § 4182A separate idling limit at 7 DE Admin. Code 1145, Excessive Idling of Heavy Duty Vehicles

The section itself

21 Del. C. § 4182, and the sentence it turns on

This is a theft provision rather than an environmental one, which is why a search for a Delaware idling law does not return it and why so much of what is written about it is written about a different statute. It sits in the vehicle code with the rules about stopping and standing, and it was put there to stop cars being driven away by somebody who did not own them.

The operative sentence is reproduced below rather than summarised, because everything that separates one state from the next in this reading sits inside it. The card carries the citation, the title the code gives the section, and the link the sentence was read from.

21 Del. C. § 4182

Highways

Unattended motor vehicle

(a) No person driving or in charge of a motor vehicle shall permit it to stand unattended without first stopping the engine, locking the ignition, removing the key and effectively setting the brake thereon and, when standing upon any grade, turning the front wheels to the curb or side of the highway.

The sentence that decides where it reaches

(a) The provisions of this title relating to the operation of vehicles refer exclusively to the operation of vehicles upon highways except: (1) Where a different place is specifically referred to in a given section.

What it turns on Prohibited, but the chapter reaches highways only
Exemptions written in 1

Title 21, Chapter 41, Subchapter XI, § 4182, Delaware Code Online, read September 23, 2026

Where the duty stops

The Delaware chapter reaches highways and stops there

A reader looking at the section alone would not see this. What confines it to a highway sits in the scope provision at the front of the chapter, reproduced below, and 20 states put it there.

This is the reading a driveway question comes down to, and it is two documents rather than one: the section that prohibits the thing and, at the front of the chapter, the sentence that says what the chapter applies to. Both are reproduced here. A city ordinance can still reach private ground, and that is a municipal question rather than a state one.

A two storey house behind a long concrete driveway with two cars parked up by the garage doors, a public footway crossing the foreground, and a thin dusting of snow over everything — Twenty of these sections sit in a chapter that reaches only a highway or a public way. The line those chapters turn on runs across the bottom of this frame, and it is nowhere in the section a reader would have found. “A dusting of snow on the front of a house and driveway along Aqueteong Lane, Ewing Township, Mercer County, New Jersey”, Famartin, CC BY-SA 4.0

What the rule lets through

The one exemption written into the Delaware section

One exemption is written into the Delaware section, each quoted below from the sentence that creates it. An exemption narrows the rule it sits in, which makes it load bearing in exactly the way that rule is, so none of them is paraphrased.

remote starter
(b) The requirements of subsection (a) of this section do not apply to an operator who starts the engine of a vehicle by using a remote starter or other similar device that remotely starts the vehicle's engine without placing the key in the ignition and requires the key to be placed in the ignition or physically present in the vehicle before the vehicle can be operated.
the sentence that creates it, read September 23, 2026

The other law entirely

Delaware also runs an emissions idling limit

Delaware does run an emissions idling limit, one of 16 states that do. 7 DE Admin. Code 1145, Excessive Idling of Heavy Duty Vehicles is the regulation and it names what it covers as heavy duty vehicles. It runs alongside the unattended vehicle section above and not instead of it: different chapter, different scope, different penalty.

The two are kept apart on this page for the same reason they are apart in the books. An unattended vehicle section sits in the vehicle code and exists to stop a car being taken. An idling limit is an air quality regulation, written by an environmental agency, aimed mostly at buses and at trucks above a weight, and enforced by somebody else. Only 16 states publish one at all, and 2 of those name the regulation without putting a figure where a reader can reach it.

A limit is set by regulation

Emissions regulation

What it covers heavy duty vehicles
Citation 7 DE Admin. Code 1145, Excessive Idling of Heavy Duty Vehicles
Published by Department of Natural Resources and Environmental Control

The limit lives in the regulation cited above, which the link opens at the section that sets it.

Department of Natural Resources and Environmental Control, read September 23, 2026

A low angle view inside an inspection garage, a car raised on a lift with a sampling hose run into its tailpipe, and an inspector standing in silhouette against the window watching it — The other law on these pages. An idling limit is an air quality regulation, written by an environment department, measured in minutes of engine running, and it is what most searches about this return. “Car being checked at an auto emission inspection station in Norwood, Ohio (DOCUMERICA, NARA 557848)”, Lyntha Scott Eiler for the U.S. Environmental Protection Agency, Public Domain

How Delaware compares

The same question in the other forty nine

34 states prohibit leaving a car running unattended and 16 have no section for it. Of the 34, 9 turn on whether the car was left unsecured, 20 sit in a chapter that reaches a road and nothing else, and 5 apply wherever the car is standing.

The bar splits the fifty by what their section does, and the table beneath it puts the strictest reading first, which is not the order a reader would guess from a map of how cold it gets.

5Always

9If unlocked

17Highways

3Public ways

16No section

Fifty state vehicle codes read September 23, 2026, strictest reading first.
State	What the section does	Citation	Turns on the lock	Separate idling limit
Kentucky	AlwaysProhibited wherever the car is standing	KRS 189.430	No	No
Louisiana	AlwaysProhibited wherever the car is standing	La. R.S. 32:145	No	No
Nevada	AlwaysProhibited wherever the car is standing	NRS 484B.530	No	No
Utah	AlwaysProhibited wherever the car is standing	Utah Code 41-6a-1403	No	No
Vermont	AlwaysProhibited wherever the car is standing	23 V.S.A. § 1111	No	Yes
Colorado	If unlockedOnly where the car was left unlocked or the key left in it	C.R.S. 42-4-1206	Yes	No
Florida	If unlockedOnly where the car was left unlocked or the key left in it	Fla. Stat. § 316.1975	Yes	No
Idaho	If unlockedOnly where the car was left unlocked or the key left in it	Idaho Code 49-602	Yes	No
Illinois	If unlockedOnly where the car was left unlocked or the key left in it	625 ILCS 5/11-1401	Yes	Yes
Kansas	If unlockedOnly where the car was left unlocked or the key left in it	K.S.A. 8-1573	Yes	No
Maryland	If unlockedOnly where the car was left unlocked or the key left in it	Md. Code Ann., Transp. 21-1101	Yes	Yes
New Hampshire	If unlockedOnly where the car was left unlocked or the key left in it	RSA 265:72	Yes	Yes
Ohio	If unlockedOnly where the car was left unlocked or the key left in it	Ohio Rev. Code 4511.661	Yes	No
Texas	If unlockedOnly where the car was left unlocked or the key left in it	Tex. Transp. Code Sec. 545.404	Yes	Yes
Alabama	HighwaysProhibited, but the chapter reaches highways only	Ala. Code Section 32-5A-50	No	No
Alaska	HighwaysProhibited, but the chapter reaches highways only	13 AAC 02.480	No	No
California	HighwaysProhibited, but the chapter reaches highways only	Cal. Veh. Code 22515	No	Yes
Delaware	HighwaysProhibited, but the chapter reaches highways only	21 Del. C. § 4182	No	Yes
Hawaii	HighwaysProhibited, but the chapter reaches highways only	HRS 291C-121	No	No
Michigan	HighwaysProhibited, but the chapter reaches highways only	Mich. Comp. Laws 257.676	No	No
Mississippi	HighwaysProhibited, but the chapter reaches highways only	Miss. Code Ann. 63-3-909	No	No
Nebraska	HighwaysProhibited, but the chapter reaches highways only	Neb. Rev. Stat. 60-6,168	No	No
New Jersey	HighwaysProhibited, but the chapter reaches highways only	N.J.S.A. 39:4-137	No	Yes
New Mexico	HighwaysProhibited, but the chapter reaches highways only	NMSA 1978, Section 66-7-353	No	No
New York	HighwaysProhibited, but the chapter reaches highways only	N.Y. Vehicle and Traffic Law § 1210	No	Yes
Oklahoma	HighwaysProhibited, but the chapter reaches highways only	47 O.S. 11-1101	No	No
Oregon	HighwaysProhibited, but the chapter reaches highways only	ORS 811.585	No	Yes
Pennsylvania	HighwaysProhibited, but the chapter reaches highways only	75 Pa.C.S. § 3701	No	Yes
South Carolina	HighwaysProhibited, but the chapter reaches highways only	S.C. Code Ann. SECTION 56-5-2570	No	No
Tennessee	HighwaysProhibited, but the chapter reaches highways only	Tenn. Code Ann. 55-8-162	No	No
Washington	HighwaysProhibited, but the chapter reaches highways only	RCW 46.61.600	No	No
Massachusetts	Public waysProhibited, but the statute reaches a public way only	M.G.L. c. 90, § 13	No	Yes
North Carolina	Public waysProhibited, but the statute reaches a public way only	N.C.G.S. § 20-163	No	No
Rhode Island	Public waysProhibited, but the statute reaches a public way only	R.I. Gen. Laws § 31-22-1	No	Yes
Arizona	No sectionNo unattended vehicle section in the code	No section	No	No
Arkansas	No sectionNo unattended vehicle section in the code	No section	No	No
Connecticut	No sectionNo unattended vehicle section in the code	No section	No	Yes
Georgia	No sectionNo unattended vehicle section in the code	No section	No	No
Indiana	No sectionNo unattended vehicle section in the code	No section	No	No
Iowa	No sectionNo unattended vehicle section in the code	Iowa Code 321.362	No	No
Maine	No sectionNo unattended vehicle section in the code	No section	No	Yes
Minnesota	No sectionNo unattended vehicle section in the code	No section	No	No
Missouri	No sectionNo unattended vehicle section in the code	No section	No	No
Montana	No sectionNo unattended vehicle section in the code	Mont. Code Ann. 61-8-357	No	No
North Dakota	No sectionNo unattended vehicle section in the code	No section	No	No
South Dakota	No sectionNo unattended vehicle section in the code	SDCL 32-30-5	No	No
Virginia	No sectionNo unattended vehicle section in the code	No section	No	Yes
West Virginia	No sectionNo unattended vehicle section in the code	No section	No	No
Wisconsin	No sectionNo unattended vehicle section in the code	No section	No	No
Wyoming	No sectionNo unattended vehicle section in the code	W.S. 31-5-509	No	No

Delaware car idling questions

Is it illegal to leave your car running unattended in Delaware?

Delaware prohibits it, but the chapter the section sits in applies to highways and not elsewhere. So the section and its reach are two separate readings: the prohibition is in one place and the sentence that confines it to highways is in another, and 20 states are built that way. Both are set out below in their own words. A reader looking at the section alone would not see this. What confines it to a highway sits in the scope provision at the front of the chapter, reproduced below, and 20 states put it there.

Which Delaware law actually covers this?

Does it matter whether the car was locked in Delaware?

Can you leave a car running in your own driveway in Delaware?

What does Delaware charge for it?

Does Delaware have an idling limit?

How current is this?

Car idling laws in every state

Delaware studded tire lawThe other winter driving rule a state writes and a city can change, with the dates each one sets.Delaware sidewalk snow rulesHow long a city gives before the walk has to be clear, quoted from the ordinance that sets it.Delaware frozen pipesWhat the same cold morning is doing to the building the car is parked beside.Delaware first snowWhen the mornings that raise this question usually start, measured against the years behind it.

Delaware read September 23, 2026, off the state’s own published code: 21 Del. C. § 4182 and the chapter it sits in, and 7 DE Admin. Code 1145, Excessive Idling of Heavy Duty Vehicles for the separate idling limit. Every quotation above is reproduced in the source’s own wording and links back to the document it was read from. Legislatures amend these between sessions and a repealed section stays in circulation for years afterwards, so the link beside a quote is what governs on the day. What Delaware wrote is what this page carries: the offence, the clause it turns on, how far the chapter reaches, what the legislature exempted, and the sentence it set.