'My neighbourhood is fuzzy, not hard and fast': Individual and contextual associations with perceived residential neighbourhood boundaries among ageing Americans.

Neighborhoods are fluid social and spatial constructs that vary by person and place. How do residential neighborhoods shift as people age? This mixed-method study investigates how perceived neighborhood boundaries and size vary by individual and contextual characteristics. Semi-structured interviews with 125 adults aged 55-92 living in the Minneapolis (Minnesota) metropolitan area suggested that neighborhood boundaries are "fuzzy". Qualitative thematic analysis identified duration of residence and housing stability, race, life-space mobility, social capital, sense of safety, and the built and social environment as key neighborhood determinants. This informed quantitative analyses among 7,811 respondents (mean age 72) from the (REGARDS) Study who self-reported how many blocks composed their neighborhoods. We tested individual and contextual factors identified in the qualitative results as related to perceived neighborhood size. Three-level gamma regression models showed that being older, white, less educated, lower income, less physically and cognitively healthy, less active, less socially supported, and feeling unsafe were significantly associated with smaller self-reported neighborhood sizes. Further, living in less racially diverse, less dense, and less affluent areas were significantly associated with smaller neighborhoods. The mixed-methods findings deepen understanding of scale in neighborhood-based research, inform urban planning interventions, and help understand what "neighborhood" means among diverse aging Americans.