by Alison Miller and Palmer Mebane

The subway stations in the grid can be matched up into pairs of stations on the same subway line. For a list of the pairs, see here.

The flavor text clues that this grid is actually two puzzles superimposed. Each puzzle is a link-a-pix puzzle, where each pair of stations must be joined by a path on the grid of length equal to the distance between the two stations on the line, and of color equal to the color of the link.

(The following observations are helpful for figuring out what is going on: (1) The sum of the lengths of all paths is twice the size of the grid. (2) The distance between any pair of stations on the grid is less than or equal to the distance on the subway line, and of the same parity.)

This logic puzzle has a unique solution, shown below.

The squares that are the same color in both grids form the following image:
.

The answer is LAST.