Memphis and Sacramento are about 1,746 miles apart by road. Split the difference and you arrive near Albuquerque, the city closest to the halfway point between them. That puts roughly 19 hr 39 min of driving on the Memphis side and 17 hr 55 min on the Sacramento side — the fairest single meeting point among the cities near the middle.
Over this distance most people will fly rather than drive the whole way. Albuquerque still makes a fair, central place for Memphis and Sacramento to converge, splitting the travel instead of asking one side to cross the country.
If Albuquerque doesn't have what you're after, Denver and El Paso are also close to the midpoint and worth a look — each keeps the drive reasonably balanced between Memphis and Sacramento.
City descriptions adapted from Wikipedia (CC BY-SA); photos via Wikimedia Commons, credited above.