Partnered with the 格助詞（かくじょし） (case-marking particle) に, the う-Verb 渡（わた）る ‘to cross’ in its て-form highlights a span of something in regard to breadth, size, or time. This structure is often translated as either ‘across (A)’, ‘throughout (A)’, ‘extending through (A)’. or ‘over the period of (A)’.
Like other verb structures that pair with nouns, the standard form may also be used when paired with a second noun, in order to modify that noun.
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彼（かれ）は脱獄（だつごく）後（ご）長年（ながねん）に渡（わた）って警察（けいさつ）から身（み）を隠（かく）し続（つづ）けた。
He continued to hide from the police for many years after his escape.
15年（ねん）に渡（わた）る戦争（せんそう）は、ついにその幕（まく）を閉（と）じた。
A war that has been taking place for over fifteen years has finally come to its end.
Coming from the meaning of 渡（わた）る ‘to cross’, this grammar pattern always expresses that something is either happening or exists ‘all across (A)’, or ‘from the start to the finish’. Additionally,
に渡（わた）って is considered quite formal, so will often be seen in articles or on the news.
Caution - As 渡（わた）る indicates a span of something that is being crossed, the ‘span’ must always be indicated clearly.
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今朝（けさ）に渡（わた）って行（おこな）われた会議（かいぎ）がようやく終（お）わった。
The meeting that has been going on throughout the whole morning has finally ended.
今晩（こんばん）に渡（わた）って落（お）ち続（つづ）けていたA社（しゃ）の株（かぶ）がやっと上（あ）がった。
The stock of Company A has finally risen after going down over the span of tonight.