Lower joints of aircraft wing assemblies are disclosed. In some embodiments, a lower joint includes an outboard lower wing panel, a center lower wing panel, a rib, and a lower joint assembly that includes two outboard flanges operatively coupled to the outboard lower wing panel, an inboard flange operatively coupled to the center lower wing panel, and an upper flange operatively coupled to the rib. In some embodiments, a lower joint assembly includes one or more splice plates, an upper T-fitting, and one or more intermediate plates. In some embodiments, the outboard lower wing panel, the center lower wing panel, and the lower joint assembly are constructed substantially of different materials.