Trees provide large positive externalities within neighborhoods, including noise attenuation, heat alleviation, and air pollutants removal. However, there are remarkable inequalities in tree cover across communities in the US. The wealthier and whiter neighborhoods enjoy more greenery. The disparities in tree exposure can lead to inequalities in heat exposure and health risks. In this paper, we characterize the unequal distribution of trees across neighborhoods in the US and investigate the consequences. We provide evidence that this tree inequality can be attributed to racial discrimination. First, we show that the disparity in tree over today can be traced back to a historic racially discriminatory housing policy. Second, through an audit experiment, we demonstrate that people of color are steered away from places with high tree cover in the initial stage of housing search.