531 miles
Depends on the route you take - but I would strongly recommend taking Interstate 20 through to Birmingham AL then Interstate 78 trough Tupelo MS to Memphis TN
There are 212 miles between Memphis to Nashville, assuming you are taking Interstate 40 and are going straight there. A DIRECT path from Downtown Memphis to Downtown Nashville would be approx. 196 miles.
390 miles taking I-10 WEST to I-55 NORTH (off EXIT 210), and then taking I-55 NORTH to Memphis, TN.
90 miles taking I-35.
2000 miles I-40 is shorter and quicker.
About 24 hours to go there because it can if your driving but it could take about 15 hours if your taking a aeroplane.
If we knew the distance between Louisville and Memphis along that route, we'd be able to figure out how long your uncle would have to drive before he passed your family going the other way.(I almost said "before he 'ran into' your family".)
The distance between Memphis, TN and Washington, DC is 880.32 miles driving, taking approximately 13 hours 58 minutes. (Mapquest) The distance "as the crow flies" between the two cities is 763.6 miles. (Infoplease)
About 332 miles on the southern route. About 344 if one travels through Nashville using the interstate highways.340 miles taking this route:Take I-40 EAST, from Memphis, to I-440 EAST to KNOXVILLE off EXIT 206.Take I-440 EAST, around DOWNTOWN NASHVILLE, to I-24 EAST to CHATTANOOGA.Take I-24 EAST to Chattanooga.
The driving distance between Memphis, TN and Lebanon, MO is approximately 285 miles. The driving time would be approximately 5 hours if you were to travel non-stop in good driving conditions. (The driving time does not take into consideration conditions which may extend trip time such as weather, road work and rush hour traffic in urban areas.)
127 miles taking this route:Take U.S. 51 NORTH, from Memphis, up to TN-22 SOUTH, near Union City; EXIT, and follow signs off the exit ramp to TN-22 SOUTH.Takle TM=22 SOUTH to MARTIN.
It's 176 miles from the crossroads at West & East College St, Dickson, to Civic Center Plaza in Memphis. The route runs on TN-46, then on Interstate 40 from exit 163 to exit 1C. If you want to avoid the Interstate and use TN-18 instead, the distance is a little more like 200 miles.