If you have the fare basis you can find the allowable 1-way routings on ITA.

so if your fare basis is KA00A0NP then input into the From field

LGA / F DL..KA00A0NP

You might not be able to fly via MSP but it looks like CVG and DTW are allowable.

Edit: oops that was June 15. For June 16 - MEM yes DTW yes CVG no (at least using the above fare basis).