Cite as: 585 U. S. ____ (2018) 7 Opinion of the Court what was happening within the home. Ibid. Likewise in Riley, the Court recognized the “immense storage capacity” of modern cell phones in holding that police officers must generally obtain a warrant before searching the contents of a phone. 573 U. S., at ___ (slip op., at 17). We explained that while the general rule allowing warrantless searches incident to arrest “strikes the appropriate balance in the context of physical objects, neither of its rationales has much force with respect to” the vast store of sensitive information on a cell phone. Id., at ___ (slip op., at 9). B The case before us involves the Government’s acquisition of wireless carrier cell-site records revealing the location of Carpenter’s cell phone whenever it made or received calls. This sort of digital data—personal location information maintained by a third party—does not fit neatly under existing precedents. Instead, requests for cell-site records lie at the intersection of two lines of cases, both of which inform our understanding of the privacy interests at stake. The first set of cases addresses a person’s expectation of privacy in his physical location and movements. In United States v. Knotts, 460 U. S. 276 (1983), we considered the Government’s use of a “beeper” to aid in tracking a vehicle through traffic. Police officers in that case planted a beeper in a container of chloroform before it was purchased by one of Knotts’s co-conspirators. The officers (with intermittent aerial assistance) then followed the automobile carrying the container from Minneapolis to Knotts’s cabin in Wisconsin, relying on the beeper’s signal to help keep the vehicle in view. The Court concluded that the “augment[ed]” visual surveillance did not constitute a search because “[a] person traveling in an automobile on public thoroughfares has no reasonable expectation of