にわたって

expression

throughout; over a period of; spanning

Used after a noun indicating a time period, range, or area to express that something continues or extends across that entire span. Often follows words like 長期間, 数年に, 全般に, etc.

See also: 渡る

• この研けん究きゅうは10年ねんに渡わたって行おこなわれた。

  This research was conducted over a period of ten years.

• 会かい議ぎは3時じ間かんに渡わたって続つづいた。

  The meeting continued for three hours.