Housing affordability is a growing public health crisis. At the individual-level, measures of affordability have been linked to maternal mental health, but less is known about how neighborhood-level characteristics influence wellbeing in the perinatal period. Using data from the Fragile Families and Child Wellbeing Study, which follows a national cohort of children born between 1998-2000 in United States cities and their parents, we examined associations between neighborhood-level housing affordability and maternal depression in the postpartum year. 30% of non-Hispanic Black mothers and 21% of Hispanic mothers lived in neighborhoods with high rent burdens (median rent-to-income ratio>30%), compared to 11% of non-Hispanic white mothers. Living in a rent-burdened neighborhood was associated with a 3-percentage-point increase in the risk of maternal depression in the postpartum year, even after adjusting for individual- and other neighborhood-level covariates. Individual-level housing hardships associated with depression included difficulty paying rent, staying in temporary housing, and having trouble paying utilities. Above and beyond individual-level housing support, policies that address neighborhood-level affordability may have spillover benefits for lowering the risk of depression and reducing disparities in maternal mental health.