This is the SEA-ATL permissible routing.
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ROUTING 35 FROM SEA-UA-PDX-UA-EUG/BOI/GEG/LAS/
RNO/SMF/SLC/SJC/PHX-UA-DEN-UA-
OR FROM SEA-UA-PDX-UA-SFO/ACV-UA-EUG/
BOI/GEG/LAS/RNO/SMF/SLC/SJC/PHX-UA-DEN-
UA-
VIA MSP/OMA/DSM/MKC/STL/MSN/MKE/
COS/DFW/CID/ICT/LNK/OKC/TUL/MLI/IND/
AUS/SAT/HOU-UA-CHI-UA-PIT/CLE/DTT/DAY/
CMH/IND/SYR-UA-
OR VIA MSY/ORL/TPA/MIA-UA-
OR VIA MSP/OMA/DSM/MKC/STL/MSN/MKE/
COS/DFW/CID/ICT/LNK/OKC/TUL/MLI/IND/
AUS/SAT/HOU-UA-CHI-UA-ALB/PHL/ABE/HAR/
ROA/RIC/CAK/CRW/BDL/GSO/RDU/PHF/ORF-UA-
OR VIA MSP/OMA/DSM/MKC/STL/MSN/MKE/
COS/DFW/CID/ICT/LNK/OKC/TUL/MLI/IND/
AUS/SAT/HOU-UA-CHI-UA-BUF-UA-ROC-UA-
TO WAS-UA-NYC/EWR-UA-ATL*
OR TO NYC/EWR-UA-WAS-UA-ATL*
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SEA-SFO-MCO-IAD-ATL is doable if you force an overnight in MCO...