The Low-Income Housing Tax Credit (LIHTC) is the main federal tool for producing affordable rental housing in the United States. Because its units are fixed in place for decades, each siting decision shapes the neighborhoods available to many successive low-income households. This review connects three bodies of research that are usually read separately: studies of where LIHTC developments are located, studies of how neighborhoods affect the long-run outcomes of the people who live in them, and studies of how LIHTC projects change the neighborhoods that receive them. We first describe how the program's design builds location choices into every allocation, and then organize the evidence around four questions: where projects go, why they go there, what location means for tenants, and what it means for existing residents. LIHTC properties remain clustered in higher-poverty, higher-minority areas. That clustering reflects land and construction markets, zoning, local opposition, and allocation rules as much as tenant demand. Neighborhood exposure has large effects on children's adult outcomes, yet LIHTC investment can also raise property values, reduce crime, and improve conditions in distressed neighborhoods, while its effects in higher-income areas are neutral or negative. The result is a genuine trade-off between expanding tenants' access to opportunity and reinvesting in disinvested places, and its terms vary with local context. We close by mapping policy levers to each part of the siting decision and by setting out a research agenda centered on causal identification, tenant-level outcomes, and within-city variation.