You’ve read all of your free items this month. To register, get added benefits and unlimited access to articles, Become a Member. Already a Member? Sign in. Advertising Age Article Abstract Merger Works For Omnicom, Publicis; Why Not U.S., Mexico? Border Be Gone: Welcome to USAM, the United States of America & Mexico By Rance Crain, Published on August 20, 2013 2 Want more Access, Content & Connections? Upgrade to Membership. We are glad you are enjoying Advertising Age. To get uninterrupted access and additional benefits, become a member today. Become a Member Already a member? Log in.