The Red Line was made by a Devil Fruit. (1055 Spoilers) : r/OnePiece

Watch ONE PIECE

Red line is based on the Paris meridian and One piece could refer to a legendary treasure hidden in France : r/OnePiece

One Piece: Summit War (385-516) (English Dub) Halfway Across the Grand Line! Arrival at the Red Line! - Watch on Crunchyroll

How big is the One Piece universe? We entered the new world around episode 500 and there is like 1,100. We haven't even gotten halfway or to One Piece yet. - Quora

We Are! Reading One Piece Podcast

One Piece Keeps Repeating the Same Story, & It's Ruining the Series

We Are! Reading One Piece Podcast Episode 35: Volume 35 - Captain

One Piece Episode 4 Sub/Dub Comparison: Luffy's Past – Enter Red-Haired Shanks

Angry Finale! Cross the Red Line! (One Piece 2001 Episode), Japanese Voice-Over Wikia

One Piece Special Episode 4: Koby and Makino reminisce about Shanks' influence on their lives