When flying from Portland to Botswana, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.
Portland (PDX), located 6.0 mi from the city center, is the airport you fly out of when you book flights from Portland to Botswana.
This is defined as Portland Airport (PDX) and Gaborone Sir Seretse Khama Airport (GBE). Codes like Gaborone Sir Seretse Khama Airport are often used to just call airports uniquely. Maun Airport (MUB), Kasane Airport (BBK), Francistown Airport (FRW) are other airports near this flight route and their unique identifiers/IATA codes.