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Southwestern North America is unusually rich in Cu resources (>330 Mt) that are hosted in a cluster of porphyry copper deposits. These formed in part of a magmatic arc along the southern margin of the Laramide tectonic province. An unequal distribution of Cu also occurs within the area: individual igneous centers have very different Cu endowments and are variably clustered in space and time. Tilted exposures of the Laramide arc’s upper crust provided by post-mineral extensional deformation expose links between deeper plutonic and shallow volcanic levels, and associated hydrothermal systems. Superposition of contrasting magmatic and hydrothermal systems is common on multiple scales: in individual igneous centers, mining districts, and regionally. Studies in the Tucson area highlight distinctive patterns in these systems, which are then extended to a regional synthesis of the evolution of the porphyry Cu province.The Tucson Mountains contain a late Cretaceous caldera on which both late Cretaceous and Paleocene igneous centers are superposed. The older (~73-72 Ma) Amole center contains a compositionally diverse pluton and voluminous cogenetic volcanic rocks, which are associated with numerous episodes of hydrothermal activity related to circulation of non-magmatic fluids (forming Na-Ca alteration and early IOCG-type epithermal veins and syngenetic hematite-silica), as well as weak porphyry-type magmatic-hydrothermal features. Several small, younger (60-57 Ma) centers contain compositionally homogeneous felsic igneous rocks, relatively minor volcanism, and are associated with better-developed but not economically significant porphyry Cu hydrothermal systems. These are similar in age and style to large porphyry Cu systems in the nearby mountain ranges (e.g., Sierrita, Pima, Rosemont) which have been extensionally dismembered. Extension here is unusual in that it occurred simultaneously in multiple directions. It is reconstructed to show that the porphyry deposits belong