`  I've just reverted the change in Chapeltown, Leeds: the text refers to ``the 1880s``, ``the next decade`` and ``by the turn of the century``, so it is not in the least ambiguous and there is no need to replace it by a clunky alternative. If ``turn of the century`` is ambiguous in a particular context (and I think we can agree that ``turn of the nth century`` is also ambiguous), then perhaps in most cases ``the start of the nth century`` would be a better form of words. ``Turn of the 19th to 20th century`` is ugly and I've never heard it used; please let's avoid it.   The Turn of the century article you link above quotes teh Chicago manual of style as saying the same: ``they recommend using only ``turn of the century,`` and only in a context that makes clear which transition is meant`` - it does not recommend using a cumbersome construction such as yours. (The usually helpful Guardian Style Guide is unfortunately silent on the question, both under ``C`` and ``T``.)  `