All the airports that United Airlines flights have come from See the airports that United Airlines flight have traveled to / or see all the flights this airline has flown (in and out of SFO)

Antonio B Won Pat International Airport. This airport in Guam is also referred to as GUM or sometimes PGUM
Guanacaste Airport. This airport in Costa Rica is also referred to as LIR or sometimes MRLB
Dane County Regional Airport-Truax Field. This airport in the United States is also referred to as MSN or sometimes KMSN
Jianoiao Airport. This airport in China is also referred to as ZSHC
Mammoth June Lakes Airport. This airport in the United States is also referred to as MMH or sometimes KMMH
Oakland International Airport. This airport in the United States is also referred to as OAK or sometimes KOAK
Northwest Arkansas Regional Airport. This airport in the United States is also referred to as XNA or sometimes KXNA
Hsien Yang Airport. This airport in China is also referred to as XIY or sometimes ZLXY
Yampa Valley Airport. This airport in the United States is also referred to as HDN or sometimes KHDN
Roswell Industrial Air Center. This airport in the United States is also referred to as ROW
Xiamen Airport. This airport in China is also referred to as XMN or sometimes ZSAM
Hilo International Airport. This airport in the United States is also referred to as ITO or sometimes PHTO

All these flight data are available as openly licensed data on the sfomuseum-data GitHub account. If you'd like to read more about our efforts to archive flight data at SFO Museum have a look a the Mills Field weblog posts tagged "flightdata".