Objectives. To describe variability in the burden of firearm violence by race, income, and place in an urban context. Methods. We used Philadelphia Police Department data from 2013 to 2014 to calculate firearm assault rates within census block groups for both victim residence and event locations, stratifying by race and block group income. We used cartographic modeling to determine variations in incidence of firearm assault by race, neighborhood income, and place. Results. The overall rate of firearm assault was 5.0 times higher (95% confidence interval [CI] = 4.5, 5.6) for Black people compared with White people. Firearm assault rates were higher among Black people across all victim residence incomes. Relative risk of firearm assault reached 15.8 times higher (95% CI = 10.7, 23.2) for Black residents in the highest-income block groups when compared with high-income White individuals. Firearm assault events tended to occur in low-income areas and were concentrated in several “hot spot” locations with high proportions of Black residents. Conclusions. Profound disparity in exposure to firearm violence by race and place exists in Philadelphia. Black people were substantially more likely than White people to sustain firearm assault, regardless of neighborhood income.

Firearm injuries caused 36 252 deaths in the United States in 2015, including 22 018 (60.7%) from suicides and 12 979 (35.8%) from homicides. Despite decreases in violent deaths in the 1990s, the rate of deaths from firearm injuries remained steady from 1999 through 2015, with an increase in the firearm suicide rate from 5.96 to 6.48 per 100 000 population in the same period.^1,2 Firearms account for over 50% of suicides and two-thirds of homicides,³ and firearm injuries and deaths are an important public health issue.^4- 10

Uber, the world's largest ridesharing company, has reportedly provided over two billion journeys globally since operations began in 2010; however, the impact on motor vehicle crashes is unclear. Theoretically, ridesharing could reduce alcohol-involved crashes in locations where other modes of transportation are less attractive than driving one's own vehicle while alcohol-affected. We conducted interrupted time series analyses using weekly counts of injury crashes and the proportion that were alcohol-involved in four US cities (Las Vegas, NV; Portland, OR; Reno, NV; San Antonio, TX). We considered that a resumption of Uber operations after a temporary break would produce a more substantial change in ridership than an initial launch, so we selected cities where Uber launched, ceased, and then resumed operations (2013-2016). We hypothesized that Uber's resumption would be associated with fewer alcohol-involved crashes. Results partially supported this hypothesis. For example, in Portland, Uber's resumption was associated with a 61.8% reduction (95% confidence interval = 38.7%, 86.4%) in the alcohol-involved crash rate (an absolute decrease of 3.1 [95% confidence interval = 1.7, 4.4] alcohol-involved crashes per week); however there was no concomitant change in all injury crashes. Relationships between ridesharing and motor vehicle crashes differ between cities over time, and may depend on specific local characteristics.