Various geometries for a trailing edge cooling system for a turbine blade. The trailing edge cooling system may include a plurality of cooling circuits extending at least partially along a radial length of a trailing edge of the turbine blade. Each cooling circuit may include an outward leg extending axially toward the trailing edge, and a plurality of turn legs in fluid communication with the outward leg. The plurality of turn legs may be positioned adjacent the trailing edge. Each cooling circuit may also include a return leg positioned adjacent the outward leg and extending axially from the trailing edge. The return leg may include a first portion and a second portion. The first portion may have a first width, and a second may have a second width that is greater than the first width of the first portion.