The fair place to meet is San Antonio, TX — the city closest to the midpoint of San Diego and Tampa. From the farther side that’s about 23 hr 37 min of driving.
Recommended midpoint
San Antonio, TX
From San Diego
23 hr 37 min
1,126 mi to San Antonio
From Tampa
20 hr 29 min
977 mi to San Antonio
Tampa has the shorter trip; the split is off by about 3 hr 8 min. The alternatives below can even it out. San Diego and Tampa are about 2,086 miles apart.
San Diego and Tampa are about 2,086 miles apart by road. Split the difference and you arrive near San Antonio, the city closest to the halfway point between them. That puts roughly 23 hr 37 min of driving on the San Diego side and 20 hr 29 min on the Tampa 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. San Antonio still makes a fair, central place for San Diego and Tampa to converge, splitting the travel instead of asking one side to cross the country.
If San Antonio doesn't have what you're after, Austin and Dallas are also close to the midpoint and worth a look — each keeps the drive reasonably balanced between San Diego and Tampa.
San Antonio is a city in the U.S. state of Texas. It is the seventh-most populous city in the United States, the second-most populous city in Texas, and the second-most populous city in the Southern U.S., with a population of 1.43 million at the 2020 census. Read more →
San Diego is a city on the Pacific coast of Southern California, adjacent to the Mexico–United States border. It is the eighth-most populous city in the U.S. Read more →
Tampa is a major city on the Gulf Coast of the U.S. state of Florida and the county seat of Hillsborough County. Tampa's borders include the north shore of Tampa Bay and the east shore of Old Tampa Bay. Read more →
City descriptions adapted from Wikipedia (CC BY-SA); photos via Wikimedia Commons, credited above.
Estimates use straight-line distance and typical road speeds; real drive times vary with route and traffic.