This describes 28 thickness point shapefiles that represent true vertical thickness (TVT) values by calculating the difference between stratigraphically adjacent formation tops picked on borehole geophysical logs. In wells where adjacent formation tops are missing, no TVT value is calculated. The TVT values are a measure of vertical thickness and do not account for the structural dip of units encountered in the wellbore. In total, the dataset contains 115,789 TVT values calculated in 16,200 wells from the Williston Basin of North Dakota, South Dakota, and Montana. This is a child item of a larger data release titled "Data release for the 3D petroleum systems model of the Williston Basin, USA".