Mental health conditions represent a tremendous global public health burden, yet social inequalities in incidence and prevalence exist. Improving access to quality neighborhood amenities, such as parks and greenspace, may improve mental health. Using data from over 11,000 responses to a 2015 and 2018 population survey in southeastern Pennsylvania, USA, we fit a series of multivariable generalized linear regression models to examine whether higher greenspace exposure and perceived park access was associated with more narrow poverty, education, employment, and race/ethnicity-based inequalities in mental health. Increasing residential tree cover (within 250 meters) was associated with a statistically significant improvement in prevalence of mental health condition, especially for lower-income respondents. Efforts to maintain and increase tree canopy in poorer neighborhoods may provide important mental health benefits.