Gap is still winning in one key area

Gap is struggling. The company has been working to become the cool retailer it once was.

But even though Gap has been fighting to regain its reputation, the company still controls one crucial market: online denim sales in the United States.

Analysts from Slice Intelligence compiled data to find out which retailer sold the most denim online.

This data accounts for 291,338 online shoppers in the United States from August, 2013 to July, 2015.

Levi's comes in at a close second behind Gap, and Gap's more successful younger sibling Old Navy - while currently thriving - still can't compete with Gap in online denim sales.

CEO Art Peck knows that denim is crucial to Gap.

"Denim is coming back," Peck said on a recent earnings conference call, "which is a place that powers the brand and I believe we have really good product development in the pipeline, and those [denim and knits] are two big categories for the brand" - going to so far to call those two categories "brand drivers."