The market size presented here is the total value of clothing and shoes that were sold electronically in 2003 and 2008. It is interesting to see that online sales of clothes and shoes have grown briskly over this five-year period since it was believed that such merchandise would be harder to sell online than other things, things that people would not wish to try on before purchasing. Four Census Bureau product codes are included in this market size calculation, they are 20200 (Men’s wear); 20220 (Women’s wear); 20240 (Children’s clothes), and 20260 (Footwear).

Geographic reference: United States (based on the location of the selling entity)
Year: 2003 and 2008
Market size: Sales: $5.13 and $17.06 billion respectively, representing a 233% increase.
Source: “Table 1055. Electronic Shopping and Mail-Order Houses—Total and E-Commerce Sales by Merchandise Line,” Statistical Abstract of the United States: 2011, U.S. Census Bureau, page 663, available online here in a spreadsheet format, and here as a PDF file.
One word of clarification to help prevent any confusion about just what is being presented here. The data in the source table are provided in two columns per year, the first one called “Total,” and the second is “E-Commerce”. The column headed “Total” refers to the total sales for the industry “Electronic Shopping and Mail-Order Houses,” [NAICS 4541], and the second column is the e-commerce portion of that industry’s total. Do not confuse the “Total” column for a measure of total sales of the product line listed in that row. It is, rather, the total sales of that product line made electronically and through mail-order houses.
Original source: U.S. Department of Commerce, Bureau of the Census.