We specify and implement a test for the presence and importance of labor market networks based on residential proximity, in determining the establishments at which people work. Using matched employer-employee data at the establishment level, we measure the importance of these network effects for groups broken out by race, ethnicity, and measures of skill. The evidence indicates that these types of labor market networks do exist and play an important role in determining the establishments where workers work; that they are more important for minorities and the less skilled, especially among Hispanics; and that they appear to be race based.

We use a unique new data set that combines data on individual workers and their employers to estimate marginal productivity differentials among different types of workers. We then compare these to estimated relative wages, leading to new evidence on productivity‐based and nonproductivity‐based explanations of the determination of wages. Among our findings are (1) the higher pay of prime‐aged workers (aged 35–54) and older workers (aged 55+) is reflected in higher point estimates of their relative marginal products, and (2) for the most part, the lower relative earnings of women are not reflected in lower relative marginal products.