This is in green because it's on the district line.

这是绿色的， 因为它在地区线上。

If we go a little bit further out on the district line, it separates into three parts.

如果我们在地区线上再往外走一点， 它就会分成三个部分。

In fact, some school districts were drawing their district lines (that is, the boundaries between schools on maps) so that they followed the racial segregation of the neighborhoods themselves.

事实上，一些学区正在绘制他们的学区线（即地图上学校之间的边界），以便他们遵循社区本身的种族隔离。