We study how decades-long exposure to individuals of a given foreign descent shapes natives' attitudes and behavior toward that group. Using individualized donations data, we show that long-term exposure to a given foreign ancestry leads to more generous behavior specifically toward that group's ancestral country. Focusing on exposure to Arab Muslims to examine mechanisms, we show that long-term exposure (i) decreases explicit and implicit prejudice against Arab Muslims, (ii) reduces support for policies and political candidates hostile toward Arab Muslims, (iii) increases charitable donations to Arab countries, (iv) leads to more personal contact with Arab Muslims, and (v) increases knowledge of Arab Muslims and Islam.

Can wars breed nationalism? We argue that civilians’ indirect exposure to war fatalities can trigger psychological processes that increase identification with their nation and ultimately strengthen support for nationalist parties. We test this argument in the context of the rise of the Nazi Party after World War 1 (WW1). To measure localized war exposure, we machine-coded information on 7.5 million German soldiers who were wounded or died in WW1. Our empirical strategy leverages battlefield dynamics that cause plausibly exogenous variation in the county-level casualty fatality rate—the share of dead soldiers among all casualties. We find that throughout the interwar period, electoral support for right-wing nationalist parties, including the Nazi Party, was 2.6 percentage points higher in counties with above-median casualty fatality rates. Consistent with our proposed mechanism, we find that this effect was driven by civilians rather than veterans and areas with a preexisting tradition of collective war commemoration.