An array of sauropod taxa coexisted in Late Jurassic North America. How so many giant genera coexisted without competing for food is puzzling considering their potential metabolic requirements. One aspect of this question is neck posture, which has been much contested, both in terms of the intrinsic curvature of the neck and the resultant elevation of the head. Neck curvature is characterized by the Osteological Neutral Pose (ONP), wherein the intervertebral joints are in an undeflected state. This pose is crucial to understanding neck posture. The articulated series of presacral vertebrae 2-19 of an exceptionally well-preserved apatosaurine, BYU 18531, are used to unravel its neck posture. This study utilized photogrammetry, digital bone repair, and CT segmentation to create virtual and physical vertebral models use to articulate the neck of this specimen, sans the atlas. To facilitate comparison with other models, dorsal vertebra 1 was set with the long axis of the centrum horizontal and at a height of 5 m above ground level. The wedge-shaped first dorsal marks the broad, U-shaped intersection between the low arched back and the neck. The neck is sinusoidal. Cervical vertebrae 15-10 are slightly arched, 9-5 droop markedly, and 4-2 are slightly dorsoflexed. This pose places the skull snout 1.5 m above the ground. The physical and virtual models were nearly identical except the neck curvature is smoother and more pronounced in the physical model. The similarity between this specimen and other apatosaurines, and possibly all diplodocids, suggests they had similar neck postures and feeding habits. This ONP, combined with dentition and the shape of the implies that this apatosaurine was "grazer". Understanding the biomechanics of this specimen provides some evidence for the larger problem of how so many coeval sauropods lived in Late Jurassic North America.