The Veneficas Americana series
The Veneficas Americana series follows the shifting fortunes of a family of American warlocks and witches from the 1870s through to the present day. The first four books in the series are (or soon will be):
1876: Dreadnought & Emily
1910: Will and Jenny
Future duologies will be set in 1929, the early 1950s, the mid-1970s, the 1990s, and finally—the present day.