Where do I find a formal dress for a tall women?

My cousin is 6 1" and it took us fover but we did it. We got a strapless dress went down to feet.,and got a cute jacket. White Jean jackets look good and fabric too! I really hope this helped. jc pennys if you have one near you has like long dresses. you could even get leggings and boots too looks super cute!!!! Good luck on the dress hunting.