Methods for assembling rotor blades are provided. A method includes receiving a first portion of a rotor blade at an erection site. The method further includes receiving a second portion of the rotor blade at the erection site. The method further includes aligning the first portion and the second portion at the erection site, the first portion and the second portion supported on a fixture system when aligned. The method further includes connecting a blade component of the first portion and a blade component of the second portion together at the erection site.