The website that specializes in selling furniture in the United States is Wayfair. Wayfair is a leading online retailer of home goods, including furniture, with a vast selection and competitive pricing. According to Statista, Wayfair had a market share of 14.3% in the U.S. furniture e-commerce market as of 2021, making it the largest online furniture retailer in the country. This significant market share is attributed to several factors, including its extensive product range, user-friendly website, and efficient logistics.

One of the reasons Wayfair has become a go-to destination for furniture shopping is its extensive product selection. The website offers a wide variety of furniture styles, from modern and contemporary to traditional and rustic, catering to diverse tastes and budgets. This extensive range allows customers to find exactly what they need without having to visit multiple stores. Additionally, Wayfair's website is designed to be intuitive and easy to navigate, making the shopping experience seamless.

Another factor contributing to Wayfair's success is its efficient logistics network. The company has a robust supply chain that ensures timely delivery of products to customers' doors. Wayfair's commitment to fast and reliable shipping has helped build trust with its customers, further solidifying its position as a top furniture retailer.

Furthermore, Wayfair has leveraged technology to enhance the shopping experience. The website features a virtual room planner tool that allows customers to visualize how furniture will look in their homes before making a purchase. This innovative feature has been well-received by customers, as it helps them make more informed decisions.

In conclusion, Wayfair is the leading website specializing in selling furniture in the United States due to its extensive product selection, user-friendly website, efficient logistics, and innovative technology. These factors have contributed to its significant market share and have made it a preferred choice for many consumers looking to purchase furniture online.