In 2003, the Museum of Vertebrate Zoology (MVZ) embarked on a resurvey of Yellowstone National Park and eventually all of California to mark the centenary of the museum’s founding in 1908. The idea of a resurvey—to collect species from “same” locations as MVZ scientists had studied 100 years before—provides an excellent case study of Griesemer’s central research problems and methods. The article reprinted here is one of the first products of a collaboration between Ayelet Shavit and Jim Griesemer focused on the MVZ resurvey. The immediate problem for the biologists planning the resurvey was how to sample the “same” locations for species that MVZ collectors had previously visited long ago. Superficially, this might seem to be just a technical issue of representing uncertainty: one simply needs a tractable way to express how precisely historical location descriptions can be mapped to modern-day GPS locations. However, the biologists recognized that revisiting the “same” locations posed a much deeper problem: they could define spatial location in two different ways, both of which had clear scientific value. Shavit and Griesemer show that biologists were well aware that their options were informed by much more than an abstract mental choice among alternative descriptions of the world. For MVZ scientists, location is not simply “in their heads” as a concept. Instead, its meaning is shaped and constrained by the research practices and institutions that MVZ researchers share with other scientists and which make long-term science possible.