This ACTIVSg70k test case is built on the eastern United States. This case covers 52 areas. It bears no relation to the actual grid in this location, except that generation and load profiles are similar, based on public data. The case is provided in PowerWorld format, including binary (PWB/PWD), PowerWorld auxiliary text format, Matpower format, PSS/E raw format, and PSLF epc format. More about the data formats.
Please contact Adam Birchfield (firstname.lastname@example.org) for any questions regarding this case. The references for this case can be found here, in particular  for the base case and  for the economic data. Work  gives details for large systems with multiple areas and multiple voltage levels;  addresses reactive power planning and power flow convergence in the context of large synthetic power grids;  aims to extend synthetic network base cases for transient stability studies.