We examine how state governments adjusted spending in response to the large temporary increase in federal grants under the 2009 American Recovery and Reinvestment Act (ARRA). We concentrate our analysis on ARRA highway grants, which were especially likely to crowd out states’ own highway funding given the lack of matching requirements and according to past research on federal highway grants. The mechanism used to apportion ARRA highway grants to states allows us to isolate exogenous changes in these grants. In addition, we show that the original 1944 proposed layout of the interstate highway system strongly predicts the cross-state distribution of the ARRA highway grants and we use this layout as an alternative instrument. We find that states increased highway spending in 2010 nearly dollar-for-dollar with their apportioned grants, implying little if any crowd-out. Moreover, we find that over the entire 2009-2011 period, ARRA highway grants crowded in highway spending, resulting in roughly two dollars in spending for each dollar in grants. We show that our results are not unique to the ARRA period, but rather are consistent with a strong effect from grants dating back at least to the early 1980s. This latter result contrasts with earlier research (Knight 2002) and we document the sources of the difference.