Microsoft Flight Simulator X: Steam Edition - Toposim US Northeast

Toposim US Northeast for FSX: Steam Edition provides LOD 12 / 10m Multi-LOD terrain mesh for the whole of the Northeast of the United States, improving the accuracy of the default terrain mesh and offering a marked improvement to the landscape profile.

VFR flying over Northeast United States has never been more realistic with lakes, mountains and ground undulations all where they should be.
Please note this pack corrects the default terrain mesh and does not include any textures.

This pack includes terrain mesh for the following US States:
* Delaware * Maryland * New Jersey * New York * Pennsylvania * Virginia * West Virginia * Connecticut * Maine * Massachusetts * New Hampshire * Rhode Island * Vermont

Source:

Steam Store Description