While the relationship between urban-rural spaces and social connectedness has long been a focus of sociological inquiry, recent social and technological changes as well as methodological innovations provide new motivation to consider how place influences sociality, especially among older adults. This study uses survey and ecological momentary assessment (EMA) data from 510 adults aged 55 and older in Indiana to investigate how area type and population density affect older adults’ core social networks and momentary interactions. We find that population density and urban-rural area type produce parallel effects. Older adults residing in rural counties as well as counties marked by lower population density reported smaller, denser, and stronger personal networks compared to those residing in urban counties and counties marked by higher population density. Similarly, the momentary analysis reveals that individuals in urban areas and higher-density counties are more likely to interact with friends than be alone, whereas rural and lower-density county residents reported fewer interactions with friends. These findings extend prior research by (1) updating understanding of the relationship between place and social connectedness; (2) providing evidence of population density’s role in shaping the social opportunity structure; and (3) providing evidence that opportunities to engage with new ties may be a key mechanism through which place shapes both momentary and stable interactions.