Although it's the longest line in terms of operation kilometers, it's one of main lines on which a superior train that runs from the starting station through the terminal station has never been set on a schedule (other examples are the Chuo Main Line and the Chikuho Main Line).
営業キロこそ日本最長の路線ではあるが、起点から終点までを通して走る優等列車の設定が史上一度もない本線の一つ（他に中央本線、筑豊本線）となっている。