Through (Via / Over A Range)

Covering a span: a stretch of time, or an extent of territory.

～にわたって vs ～により: Use にわたって for the span itself (三日にわたって, 全国にわたって). により names a means or a cause and cannot measure an extent, so the two only look alike in the English 'through'.

Something passed through stages on the way to where it ended up.

Noun を経て vs ～を通じて: Use を経て. It traces a path through intermediate steps (交渉を経て合意に至った). を通じて is a channel or a continuous period something happens by or across, without that sense of stages completed one after another.