Walkability and transit. Urban morphology plays an enormous role in our public health and safety, another phenomenon that I believe is under-appreciated (despite a seeming rise in interest in this area over the last few years). This to me is one of the most important truly political problems of our era that is not at the level of an existential crisis (ie climate risk, AI risk, nuclear risk, and disease prevention). Because of that, I believe it receives less focus than it should, and is also an avenue where so many lives can be saved (e.g. car deaths still leading killer of <25 year olds in the US).