The fair place to meet is Denver, CO — the city closest to the midpoint of Portland and Tampa. From the farther side that’s about 31 hr 54 min of driving.
Recommended midpoint
Denver, CO
From Portland
20 hr 34 min
981 mi to Denver
From Tampa
31 hr 54 min
1,521 mi to Denver
Portland has the shorter trip; the split is off by about 11 hr 20 min. The alternatives below can even it out. Portland and Tampa are about 2,501 miles apart.
Portland and Tampa are about 2,501 miles apart by road. Split the difference and you arrive near Denver, the city closest to the halfway point between them. That puts roughly 20 hr 34 min of driving on the Portland side and 31 hr 54 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. Denver still makes a fair, central place for Portland and Tampa to converge, splitting the travel instead of asking one side to cross the country.
If Denver doesn't have what you're after, Albuquerque and Oklahoma City are also close to the midpoint and worth a look — each keeps the drive reasonably balanced between Portland and Tampa.
Denver is the capital and most populous city of the U.S. state of Colorado. Officially a consolidated city and county, it is located in the South Platte River valley on the western edge of the High Plains, and is just east of the Front Range of the Rocky… Read more →
Portland is the most populous city in the U.S. state of Oregon. Located in the Pacific Northwest at the confluence of the Willamette and Columbia rivers, it is the 28th-most populous city in the United States, sixth-most populous on the West Coast, and… 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.