Advertising messages compete for scarce attention. ?Junk? mail, ?spam? e-mail, and telemarketing calls need both parties to exert effort to generate transactions. Message recipients supply attention depending on average message beneÞt. Senders are motivated by proÞts. Costlier message...

This paper lays out and elaborates upon the properties of an extended Chamberlinian model with applications both in Industrial Organization and Economic Geography/ Urban Economics. The framework is used to explain the impact of some major changes over the last two centuries: reductions in...