Changing institutions is an integral part of an academic life. Yet little is known about the mobility patterns of scientists at an institutional level and how these career choices affect scientific outcomes. In the study below, the authors examine over 420,000 papers, to track the affiliation information of individual scientists, allowing them to reconstruct their career trajectories over decades. They find that career movements are not only temporally and spatially localized, but also characterized by a high degree of stratification in institutional ranking. When cross-group movement occurs, they find that while going from elite to lower-rank institutions on average