Why did US urban homicide spike in 2020? A cross-sectional data analysis for the largest American cities.

Working with data about homicide victims and perpetrators from 50 of America's largest cities, we investigate the explanatory power of some familiar explanations for why murder in those cities rose sharply in 2020. The analysis reveals that the distribution of risk by race was essentially the same in 2020 as in 2019. That empirical finding challenges some theories of how racial tensions after the death of George Floyd may have driven homicide increases.

The number of undocumented immigrants in the United States: Estimates based on demographic modeling with data from 1990 to 2016.

We apply standard demographic principles of inflows and outflows to estimate the number of undocumented immigrants in the United States, using the best available data, including some that have only recently become available. Our analysis covers the years 1990 to 2016. We develop an estimate of the number of undocumented immigrants based on parameter values that tend to underestimate undocumented immigrant inflows and overstate outflows; we also show the probability distribution for the number of undocumented immigrants based on simulating our model over parameter value ranges.