September 11 2001 terrorist attacks: 2,996 dead.[1]
Here's some data for the previous few years[2], and 2016:
In 2016, 10,497 people died in alcohol-impaired driving crashes, accounting for 28% of all traffic-related deaths in the United States.[3]
1. https://en.wikipedia.org/wiki/Casualties_of_the_September_11...
2. https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/...
3 . https://www.cdc.gov/motorvehiclesafety/impaired_driving/impa...
