How does online cross-border shopping affect state use tax liabilities? We collect our own data on actual online cross-border shopping transactions from eBay.com, focusing upon a "representative" commodity classification and a "typical" day. These data allow us to examine the extent of actual online cross-border shopping by buyers, and the subsequent potential impact on state use tax liabilities of buyers. Our results indicate that online cross-border shopping is highly prevalent on eBay, with out-of-state purchases accounting for on average 94 percent of the volume of a state's online purchase transactions. Even so, given the limited volume of eBay- based transactions relative to total sales transactions, the likely impact of cross-border transactions on state use tax revenue streams is negligible, even if we assume full buyer compliance with state use taxes.