The purpose of the present study is to provide policy implications for successful development of the metropolitan economic zone in Korea followed by in-depth case studies on the US Metropolitan Economic Region. This study looked into diverse experiences of the US mega regions investigating their key strategies, requirements and standards, etc. Urban areas in the US are designated based on CBSA, a standard for statistical area since 1950. The US has a clear standard to define rural and suburban area and is trying to reflect urban structural changes including suburbanization. The US annexation system is relatively simple to operate. Furthermore, the system helps the growth of rural areas by gradually incorporating rural areas into urban areas. We found that action plans of the US mega regions facilitate strategic growth and development for balanced territorial development, incorporating multi-dimensional and comprehensive approaches. We also found that the US mega regions are designated with regard to the local natures. Couple of policy implications were extracted from the US experiences. First, since the construction of mega regions in Korea concerns less on the inter-regional connections with other regions, we need to incorporate diverse standards to divide the regions with respect to the spatial and local characteristics. Second, local governments should collaborate with each other for successful economic development of the metropolitan economic zones. Administrative districts renovation can be a immediate and effective solution to facilitate the collaboration. We recommended to consider consolidating administrative areas to construct successful metropolitan economic zones.