Where did Kagami Taiga live when he lived in the US?
The only indication offhand gets kinda spoilery but 

Character Spoiler: 


   Unrevealed yet in the anime as of episode 1 of Kuroko no Basket S2, Alexandra Garcia, was a college champion in the NCAA from UCLA. In her retirement, she frequented betting courts on the streets (which could technically be anywhere) and eventually runs into Taiga &amp; Himuro. 


Event Spoiler:


   Alexandra trains Taiga &amp; Himuro as kids. Later on Taiga decides to receive training once more from his old master by returning to Los Angeles, so it's pretty suggested that everything took place in SoCal. Here's a pic of an announced airline destination: Chapter 111, page 19 from Batoto.net


I tried to minimize unnecessary spoiling information. Overall, a bit circumstantial, but still enough for me to presume that they're in Southern California.