New social transformations within and beyond the cities of classic urban studies challenge prevailing accounts of spatial inequality. This paper pivots from the Rust Belt to the Sunbelt accordingly, disentangling persistence and change in neighborhood median income and concentrated income extremes in Los Angeles County. We first examine patterns of change over two decades starting in 1990 for all Los Angeles neighborhoods. We then analyze an original longitudinal study of approximately six hundred Angelenos from 2000 to 2013, assessing the degree to which contextual changes in neighborhood income arise from neighborhood-level mobility or individual residential mobility. Overall we find deep and persistent inequality among both neighborhoods and individuals. Contrary to prior research, we also find that residential mobility does not materially alter neighborhood economic conditions for most race, ethnic, and income groups. Our analyses lay the groundwork for a multilevel theoretical framework capable of explaining spatial inequality across cities and historical eras.