Two years ago, a Montana think tank called the Frontier Institute released a new tool to help push the group’s advocacy for pro-housing reforms: a zoning atlas, one of the first of its kind. The atlas used parcel-level data to analyze local regulations that restrict how and where homes can be built, an issue for a state with skyrocketing housing costs. The study revealed that more than 70% of residential areas in Montana’s most in-demand communities prohibited the construction of even modest duplex homes, much less apartment buildings.