Within the academic field of history, what are the most common specializations in terms of time period, region, and type (i.e. cultural, intellectual, etc.) of history, particularly in the English-speaking world?

by RingGiver
sunagainstgold

The American Historical Association has some data that might interest you:

More informally but with greater breakdowns within subfields, the Academic Jobs Wiki records listed academic jobs and asks (but obviously can't require) visitors post their own specialty: