Chief Justice Burger
delivered the opinion of the Court.
We granted certiorari to decide whether law enforcement agents violated the Fourth Amendment when they conducted a warrantless search, based on probable cause, of a fully mobile “motor home” located in a public place.
H-I
On May 31, 1979, Drug Enforcement Agency Agent Robert Williams watched respondent, Charles Carney, approach a youth in downtown San Diego. The youth accompanied Carney to a Dodge Mini Motor Home parked in a nearby lot. Carney and the youth closed the window shades in the motor home, including one across the front window. Agent Williams had previously received uncorroborated information that the same motor home was used by another person who was exchanging marihuana for sex. Williams, with assistance from other agents, kept the motor home under surveillance for the entire one and one-quarter hours that Carney and the youth remained inside. When the youth left the motor home, the agents followed and stopped him. The youth told the agents that he had received marihuana in return for allowing Carney sexual contacts.
At the agents’ request, the youth returned to the motor home and knocked on its door; Carney stepped out. The agents identified themselves as law enforcement officers. Without a warrant or consent, one agent entered the motor home and observed marihuana, plastic bags, and a scale of the kind used in weighing drugs on a table. Agent Williams took Carney into custody and took possession of the motor home. A subsequent search of the motor home at the police station revealed additional marihuana in the cupboards and refrigerator.
Respondent was charged with possession of marihuana for sale. At a preliminary hearing, he moved to suppress the evidence discovered in the motor home. The Magistrate denied the motion, upholding the initial search as a justifiable search for other persons, and the subsequent search as a routine inventory search.
Respondent renewed his suppression motion in the Superior Court. The Superior Court also rejected the claim, holding that there was probable cause to arrest respondent, that the search of the motor home was authorized under the automobile exception to the Fourth Amendment’s warrant requirement, and that the motor home itself could be seized without a warrant as an instrumentality of the crime. Respondent then pleaded nolo contendere to the charges against him, and was placed on probation for three years.
Respondent appealed from the order placing him on probation. The California Court of Appeal affirmed, reasoning that the vehicle exception applied to respondent’s motor home. 117 Cal. App. 3d 36, 172 Cal. Rptr. 430 (1981).
The California Supreme Court reversed the conviction. 34 Cal. 3d 597, 668 P. 2d 807 (1983). The Supreme Court did not disagree with the conclusion of the trial court that the agents had probable cause to arrest respondent and to believe that the vehicle contained evidence of a crime; however, the court held that the search was unreasonable because no warrant was obtained, rejecting the State’s argument that the vehicle exception to the warrant requirement should apply. That court reached its decision by concluding that the mobility of a vehicle “is no longer the prime justification for the automobile exception; rather, ‘the answer lies in the diminished expectation of privacy which surrounds the automobile.’” Id., at 605, 668 P. 2d, at 811. The California Supreme Court held that the expectations of privacy in a motor home are more like those in a dwelling than in an automobile because the primary function of motor homes is not to provide transportation but to “provide the occupant with living quarters.” Id., at 606, 668 P. 2d, at 812.
We granted certiorari, 465 U. S. 1098 (1984). We reverse.
1 — 1 I — I
The Fourth Amendment protects the right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures.” This fundamental right is preserved by a requirement that searches be conducted pursuant to a warrant issued by an independent judicial officer. There are, of course, exceptions to the general rule that a warrant must be secured before a search is undertaken; one is the so-called “automobile exception” at issue in this case. This exception to the warrant requirement was first set forth by the Court 60 years ago in Carroll v. United States, 267 U. S. 132 (1925). There, the Court recognized that the privacy interests in an automobile are constitutionally protected; however, it held that the ready mobility of the automobile justifies a lesser degree of protection of those interests. The Court rested this exception on a long-recognized distinction between stationary structures and vehicles:
“[T]he guaranty of freedom from unreasonable searches and seizures by the Fourth Amendment has been construed, practically since the beginning of Government, as recognizing a necessary difference between a search of a store, dwelling house or other structure in respect of which a proper official warrant readily may be obtained, and a search of a ship, motor boat, wagon or automobile, for contraband goods, where it is not practicable to secure a warrant because the vehicle can be quickly moved out of the locality or jurisdiction in which the warrant must be sought.” Id., at 153 (emphasis added).
The capacity to be “quickly moved” was clearly the basis of the holding in Carroll, and our cases have consistently recognized ready mobility as one of the principal bases of the automobile exception. See, e. g., Cooper v. California, 386 U. S. 58, 59 (1967); Chambers v. Maroney, 399 U. S. 42, 52 (1970); Cady v. Dombrowski, 413 U. S. 433, 442 (1973); Cardwell v. Lewis, 417 U. S. 583, 588 (1974); South Dakota v. Opperman, 428 U. S. 364, 367 (1976). In Chambers, for example, commenting on the rationale for the vehicle exception, we noted that “the opportunity to search is fleeting since a car is readily movable.” 399 U. S., at 51. More recently, in United States v. Ross, 456 U. S. 798, 806 (1982), we once again emphasized that “an immediate intrusion is necessary” because of “the nature of an automobile in transit. . . .” The mobility of automobiles, we have observed, “creates circumstances of such exigency that, as a practical necessity, rigorous enforcement of the warrant requirement is impossible.” South Dakota v. Opperman, supra, at 367.
However, although ready mobility alone was perhaps the original justification for the vehicle exception, our later cases have made clear that ready mobility is not the only basis for the exception. The reasons for the vehicle exception, we have said, are twofold. 428 U. S., at 367. “Besides the element of mobility, less rigorous warrant requirements govern because the expectation of privacy with respect to one’s automobile is significantly less than that relating to one’s home or office.” Ibid.
Even in cases where an automobile was not immediately mobile, the lesser expectation of privacy resulting from its use as a readily mobile vehicle justified application of the vehicular exception. See, e. g., Cady v. Dombrowski, supra. In some cases, the configuration of the vehicle contributed to the lower expectations of privacy; for example, we held in Cardwell v. Lewis, supra, at 590, that, because the passenger compartment of a standard automobile is relatively open to plain view, there are lesser expectations of privacy. But even when enclosed “repository” areas have been involved, we have concluded that the lesser expectations of privacy warrant application of the exception. We have applied the exception in the context of a locked car trunk, Cady v. Dombrowski, supra, a sealed package in a car trunk, Ross, supra, a closed compartment under the dashboard, Cham bers v. Maroney, supra, the interior of a vehicle’s upholstery, Carroll, supra, or sealed packages inside a covered pickup truck, United States v. Johns, 469 U. S. 478 (1985).
These reduced expectations of privacy derive not from the fact that the area to be searched is in plain view, but from the pervasive regulation of vehicles capable of traveling on the public highways. Cady v. Dombrowski, supra, at 440-441. As we explained in South Dakota v. Opperman, an inventory search case:
“Automobiles, unlike homes, are subjected to pervasive and continuing governmental regulation and controls, including periodic inspection and licensing requirements. As an everyday occurrence, police stop and examine vehicles when license plates or inspection stickers have expired, or if other violations, such as exhaust fumes or excessive noise, are noted, or if headlights or other safety equipment are not in proper working order.” 428 U. S., at 368.
The public is fully aware that it is accorded less privacy in its automobiles because of this compelling governmental need for regulation. Historically, “individuals always [have] been on notice that movable vessels may be stopped and searched on facts giving rise to probable cause that the vehicle contains contraband, without the protection afforded by a magistrate’s prior evaluation of those facts.” Ross, supra, at 806, n. 8. In short, the pervasive schemes of regulation, which necessarily lead to reduced expectations of privacy, and the exigencies attendant to ready mobility justify searches without prior recourse to the authority of a magistrate so long as the overriding standard of probable cause is met.
When a vehicle is being used on the highways, or if it is readily capable of such use and is found stationary in a place not regularly used for residential purposes — temporary or otherwise — the two justifications for the vehicle exception come into play. First, the vehicle is obviously readily mobile by the turn of an ignition key, if not actually moving. Second, there is a reduced expectation of privacy stemming from its use as a licensed motor vehicle subject to a range of police regulation inapplicable to a fixed dwelling. At least in these circumstances, the overriding societal interests in effective law enforcement justify an immediate search before the vehicle and its occupants become unavailable.
While it is true that respondent’s vehicle possessed some, if not many of the attributes of a home, it is equally clear that the vehicle falls clearly within the scope of the exception laid down in Carroll and applied in succeeding cases. Like the automobile in Carroll, respondent’s motor home was readily mobile. Absent the prompt search and seizure, it could readily have been moved beyond the reach of the police. Furthermore, the vehicle was licensed to “operate on public streets; [was] serviced in public places;. . . and [was] subject to extensive regulation and inspection.” Rakas v. Illinois, 439 U. S. 128, 154, n. 2 (1978) (Powell, J., concurring). And the vehicle was so situated that an objective observer would conclude that it was being used not as a residence, but as a vehicle.
Respondent urges us to distinguish his vehicle from other vehicles within the exception because it was capable of functioning as a home. In our increasingly mobile society, many vehicles used for transportation can be and are being used not only for transportation but for shelter, i. e., as a “home” or “residence.” To distinguish between respondent’s motor home and an ordinary sedan for purposes of the vehicle exception would require that we apply the exception depending upon the size of the vehicle and the quality of its appointments. Moreover, to fail to apply the exception to vehicles such as a motor home ignores the fact that a motor home lends itself easily to use as an instrument of illicit drug traffic and other illegal activity. In United States v. Ross, 456 U. S., at 822, we declined to distinguish between “worthy” and “unworthy” containers, noting that “the central purpose of the Fourth Amendment forecloses such a distinction. ” We decline today to distinguish between “worthy” and “unworthy” vehicles which are either on the public roads and highways, or situated such that it is reasonable to conclude that the vehicle is not being used as a residence.
Our application of the vehicle exception has never turned on the other uses to which a vehicle might be put. The exception has historically turned on the ready mobility of the vehicle, and on the presence of the vehicle in a setting that objectively indicates that the vehicle is being used for transportation. These two requirements for application of the exception ensure that law enforcement officials are not unnecessarily hamstrung in their efforts to detect and prosecute criminal activity, and that the legitimate privacy interests of the public are protected. Applyingthe vehicle exception in these circumstances allows the essential purposes served by the exception to be fulfilled, while assuring that the exception will acknowledge legitimate privacy interests.
III
The question remains whether, apart from the lack of a warrant, this search was unreasonable. Under the vehicle exception to the warrant requirement, “[ojnly the prior approval of the magistrate is waived; the search otherwise [must be such] as the magistrate could authorize.” Ross, supra, at 823.
This search was not unreasonable; it was plainly one that the magistrate could authorize if presented with these facts. The DEA agents had fresh, direct, uncontradicted evidence that the respondent was distributing a controlled substance from the vehicle, apart from evidence of other possible offenses. The agents thus had abundant probable cause to enter and search the vehicle for evidence of a crime notwithstanding its possible use as a dwelling place.
The judgment of the California Supreme Court is reversed, and the case is remanded for further proceedings not inconsistent with this opinion.
It is so ordered.
Respondent contends that the state-court decision rests on an adequate and independent state ground, because the opinion refers to the State as well as the Federal Constitution. Respondent’s argument is clearly foreclosed by our opinion in Michigan v. Long, 463 U. S. 1032, 1040-1041 (1983), in which we held, “when... a state court decision fairly appears to rest primarily on federal law, or to be interwoven with the federal law, and when the adequacy and independence of any possible state law ground is not clear from the face of the opinion, we will accept as the most reasonable explanation that the state court decided the case the way it did because it believed that federal law required it to do so.” We read the opinion as resting on federal law.
With few exceptions, the courts have not hesitated to apply the vehicle exception to vehicles other than automobiles. See, e. g., United States v. Rollins, 699 F. 2d 530 (CA11) (airplane), cert. denied, 464 U. S. 933 (1983).
We need not pass on the application of the vehicle exception to a motor home that is situated in a way or place that objectively indicates that it is being used as a residence. Among the factors that might be relevant in determining whether a warrant would be required in such a circumstance is its location, whether the vehicle is readily mobile or instead, for instance, elevated on blocks, whether the vehicle is licensed, whether it is connected to utilities, and whether it has convenient access to a public road.