Abstract: When does the Dormant Commerce Clause preclude states from regulating internet activity--whether through state libel law or invasion of privacy law; through state laws requiring websites to accommodate disabled users (for instance, by providing closed captioning); through state bans on discriminating based on sexual orientation, religion, or criminal record; or through state laws that ban social media platforms from discriminating based on the viewpoint of users' speech? This Article argues that the constitutionality of such state regulation should generally turn on the feasability of geolocation--the extent to which websites or other internet services can determine, reliably and inexpensively, which states users are coming from so that the sites can then apply the proper state law to each user (or, if need be, choose not to allow access to users from certain states). In recent years, geolocation has become feasible and is routinely used by major websites for ordinary business purposes. There is therefore more constitutional room for state regulation of internet services, including social media platforms, than often believed.