I study Los Angeles Metro Rail's effects using panel data on bilateral commuting flows, a quantitative spatial model, and historically motivated quasi-experimental research designs. The model separates transit's commuting effects from local productivity or amenity effects, and spatial shift-share instruments identify inelastic labor and housing supply. Metro Rail connections increase commuting by 16% but do not have large effects on local productivity or amenities. Metro Rail generates $94 million in annual benefits by 2000 or 12–25% of annualized costs. Accounting for reduced congestion and slow transit adoption adds, at most, another $200 million in annual benefits.

Does social distancing harm innovation? We estimate the effect of non-pharmaceutical interventions (NPIs)—policies that restrict interactions in an attempt to slow the spread of disease—on local invention. We construct a panel of issued patents and NPIs adopted by 50 large US cities during the 1918 flu pandemic. Difference-in-differences estimates show that cities adopting longer NPIs did not experience a decline in patenting during the pandemic relative to short-NPI cities, and recorded higher patenting afterward. Rather than reduce local invention by restricting localized knowledge spillovers, NPIs adopted during the pandemic may have preserved other inventive factors.

Technology adoption often requires multiple stages of investment. As new information emerges, agents may abandon a technology that was profitable in expectation. We use a field experiment to vary the payoffs at two stages of investment in a new technology: a tree species that provides on-farm fertilizer benefits. Farmer decisions identify the information about profitability that arrives between the take-up and follow-through stages. Results show that this form of uncertainty increases take-up but lowers average tree survival, decreasing the cost-effectiveness of take-up subsidies. Thus, uncertainty offers another explanation for why even costly technologies may go unused or be abandoned.