New Jersey
Best Decade: 1920s (+1.38 Seats)
Reason: lots of children of immigrants leaving the lower east side?
Worst Decade: 1970s (-1.19 Seats)
Reason: baby boomers moving out of the house?
Nope, just an ass-load of immigrants from Italy and Ireland. Then the massive decline in the state's urban areas.
Yep, this is largely a factor of the explosive industrial growth of Newark and Jersey City from 1900-1930 (fueled largely by the Irish and Italian labor on the docks and factories) and then the collapse in aftermath of 67 Newark riots and racial tensions/white flight in general.
