Kentucky has created a guide for its community outlining why the state supports the Common Core. Although specifically made for Kentucky, the 10 points are applicable to all states working with the CCSS. Among the reasons are the financial advantages including the fact that a great set of materials created in New York, Louisiana, Arizona or Montana are of equal value to all participating states.
Leveraging the talent in all 45 CCSS states towards one outcome is a boom to districts, with tight budgets, trying to make sure students are working with great resources. Many of those free and vetted materials are now linked here.