Originally Posted by
Serpent
Like others have said, yes, you need a ESTA. Be ready to pull it up on your phone at the counter too, i had to do that when I was catching my flight from IAD couple of days ago because they couldn't see my ESTA in the system.
This is 100% wrong.
OP states that he is a US national traveling on a US passport and traveling from the US. An ESTA is the electronic travel approval the US requires for non-US nationals traveling from visa waiver program countries to the US. Thus, on all three counts, he does not need an ESTA and one will not be issued if he wastes $14 applying. It also will not move him one inch closer to Australia.
As a US national he will require an Electronic Travel Authority from the Australian Home Office. This is an electronic link tied to the passenger's passport. All accomplished online.
On the broader topic, anyone traveling across a border would do well to review his specific document requirement situation on TIMATIC, the IATA database compiled for its member air carriers. There are a number of portals providing free access. One of them at the link below. What OP sees when he fills in his data is what the check-in agent will see at check-in.
https://www.united.com/web/en-US/app...aspx?i=TIMATIC