Amazon Says More Than a Million U.S. Small Businesses Sell on Its Site

Retail giant discloses figure for the first time as criticism about its economic impact grows

Amazon.com Inc. said more than one million small businesses in the U.S. sell their wares on its online marketplace, providing the number for the first time amid criticism from some politicians over its business practices and economic impact.

The Seattle-based retailer has previously said that it had more than two million total third-party sellers world-wide, but hadn’t given a breakdown in the U.S. In its release on Thursday, it also listed the number of smaller merchants by state, saying California had the most with more...