The Ridge-and-Valley Appalachians form a broad arc between the Blue Ridge Mountains, which is located where?
Ridge-and-Valley Appalachians:  They form a broad arc between the Blue Ridge Mountains and the Appalachian Plateau physiographic province (the Allegheny and Cumberland Plateaus). Blue Ridge Mountains:  The mountain range is located in the eastern United States, starting at its southernmost portion in Georgia, then ending northward in Pennsylvania.
the eastern United States, starting at its southernmost portion in Georgia, then ending northward in Pennsylvania