Amazon is expected to surpass Macy's as the top clothing retailer in the U.S. by 2017.

The online retailer's success is largely due to its accessories department, according to Cowen analysts in a note sent to Business Insider.

Amazon now offers several brands typically found in department stores, such as Levi's and Tommy Hilfiger. The company is able to list these items at lower prices because they do not have to pay overhead costs for retail stores.

According to Bloomberg, the analysts expect Amazon's apparel gross merchandise value to grow from $16 billion in 2015 to $52 billion in 2020.

Amazon's apparel purchasers have grown approximately 29 percent each year whereas competitors like Target and Walmart have seen a 2-3 percent decline.

Kohl's reported poor first quarter earnings for 2015, with shares falling more than 11 percent.

Amazon has been fighting for the top spot, most recently with their highly-anticipated but poorly-reviewed Amazon Prime Day.