2 CARPENTER v. UNITED STATES Syllabus prepared to recognize as reasonable,” official intrusion into that sphere generally qualifies as a search and requires a warrant supported by probable cause. Smith v. Maryland, 442 U. S. 735, 740 (internal quotation marks and alterations omitted). The analysis regarding which expectations of privacy are entitled to protection is informed by historical understandings “of what was deemed an unreasonable search and seizure when [the Fourth Amendment] was adopted.” Carroll v. United States, 267 U. S. 132, 149. These Founding-era understandings continue to inform this Court when applying the Fourth Amendment to innovations in surveillance tools. See, e.g., Kyllo v. United States, 533 U. S. 27. Pp. 4–7. (b) The digital data at issue—personal location information maintained by a third party—does not fit neatly under existing precedents but lies at the intersection of two lines of cases. One set addresses a person’s expectation of privacy in his physical location and movements. See, e.g., United States v. Jones, 565 U. S. 400 (five Justices concluding that privacy concerns would be raised by GPS tracking). The other addresses a person’s expectation of privacy in information voluntarily turned over to third parties. See United States v. Miller, 425 U. S. 435 (no expectation of privacy in financial records held by a bank), and Smith, 442 U. S. 735 (no expectation of privacy in records of dialed telephone numbers conveyed to telephone company). Pp. 7–10. (c) Tracking a person’s past movements through CSLI partakes of many of the qualities of GPS monitoring considered in Jones—it is detailed, encyclopedic, and effortlessly compiled. At the same time, however, the fact that the individual continuously reveals his location to his wireless carrier implicates the third-party principle of Smith and Miller. Given the unique nature of cell-site records, this Court declines to extend Smith and Miller to cover them. Pp. 10–18. (1) A majority of the Court has already recognized that individuals have a reasonable expectation of privacy in the whole of their physical movements. Allowing government access to cell-site records—which “hold for many Americans the ‘privacies of life,’ ” Riley v. California, 573 U. S. ___, ___—contravenes that expectation. In fact, historical cell-site records present even greater privacy concerns than the GPS monitoring considered in Jones: They give the Government near perfect surveillance and allow it to travel back in time to retrace a person’s whereabouts, subject only to the five-year retention policies of most wireless carriers. The Government contends that CSLI data is less precise than GPS information, but it thought the data accurate enough here to highlight it during closing argument in Carpenter’s trial. At any rate, the rule the Court adopts “must take account of more sophisticated systems that are already in use or in