Why did Gatsby go to Louisville when he came back to the US?

Gatsby returned to Louisville to relive his time with Daisy.

He came back from France when Tom and Daisy were still on their wedding trip, and made a miserable but irresistible journey to Louisville on the last of his army pay. He stayed there a week, walking the streets where their footsteps had clicked together through the November night and revisiting the out-of-the-way places to which they had driven in her white car. Just as Daisy’s house had always seemed to him more mysterious and gay than other houses, so his idea of the city itself, even though she was gone from it, was pervaded with a melancholy beauty.