Sisterhood of the Travelling Pants came out more than 10 years ago, but the cast is still closer than ever. Just like their characters in the book-to-movie franchise, Blake Lively, Amber Tamblyn, Alexis Bledel, and America Ferrera have been by each others' sides as they navigate motherhood, friendship, and just being incredibly strong and inspirational women. Honestly, it's no wonder fans are begging for a third movie. We just can't get enough of their incredible bond, on and off screen. They may not be related by blood, but these four will always be united through their epic sisterhood.