I have a 2001 Impala. The fuse for the tail lights (rear parking lights) is blown and I can not locate a obvious short. Also, the instrument panel lights are out.
So you replaced the fuse and it blew again?
You need to disconnect the loads that draw through that fuse one by one until the fuse doesn’t blow.
“You need to disconnect the loads that draw through that fuse one by one until the fuse doesn’t blow.”
You might try connecting loads until it blows, That you you only blow one fuse. 
I guess I was thinking the head was on the wrong end of the nail ;o)
If you have a connector for a trailer hitch or added accessory like a stereo those are likely places to look for the short. The trouble could be with the dash lighting also besides the running lights circuit.