SB 1070 didn't have to go into effect to have an impact
Share of surveyed undocumented migrants in Mexican border towns who report an intended destination in various states. The share of migrants heading to Arizona fell sharply in the months when SB 1070 was in the news, even before its provisions took effect. 
 
Note: values are five-month centered moving averages.
Source: author data from EMIF migration survey