にわたって

にわたって says that something covers the whole of a period, a series or an area: "over", "throughout", "across". It follows a noun for a length of time, a number of times, or a range of places or fields.

The noun gives the whole extent, and the point is that it is long or wide. It is formal, at home in news reports and written Japanese. In conversation ずっと or a plain duration does the job: ご5じかん時間かいぎ会議をした.

にわたる before a noun

To describe a noun, use にわたる, or the past にわたった.

• × 10年にわたって努力 → 10年にわたる努力

にわたって or にかけて

にかけて names a span by its two ends, usually with から, and the edges are rough: "from about A to about B". にわたって takes a single noun for the whole length.

• × 三日間にかけて → 三日間にわたって

にわたり

にわたり is the same pattern ending a clause in written style, without the て.