16Dispersal is a fundamental ecological process, and population density has been observed as a 17 driver of dispersal in various taxa. Conflicting examples of positive and negative density-18 dependent dispersal, however, leave little consensus regarding any general effects of density on 19 dispersal. Deer mice (Peromyscus maniculatus) have exhibited both negative and positive 20 density-dependent dispersal. Using 51-years of data on P. maniculatus live-trapping 21 abundances, we examined the spatial scale of density-dependent dispersal as well as its temporal 22 stability within this long time-series. We examined these patterns over both the entire time-series 23 and also in ten-year shifting windows to determine whether the nature and strength of the 24 relationship changed through time. Overall, the probability of dispersal decreased with increased 25 local and regional population density, and the negative effect of local density on dispersal was 26 more pronounced in years with low regional densities. Females were less likely to disperse, but 27 female dispersal was more density-dependent than male dispersal. Additionally, the strength of 28 negative density-dependent dispersal changed through time, from very strong in some decades to 29 absent in others. Our study shows that the relationship between density and dispersal is not 30 temporally static and that studies of density-dependent dispersal should consider both local and 31 regional population densities. As well, while male-biased dispersal is often considered 32 ubiquitous in mammals, we demonstrate that male and female dispersal may have differing 33 levels of density-dependence. Finally, our study highlights the importance of accounting for both 34 local and regional processes in natural systems as these types of long-term, spatially broad 35 examinations of dispersal are crucial if spatial processes are to be represented adequately and 36 accurately in population modelling and theory. 37