Check out a website called the Great Circle Mapper:

www.gcmap.com

It allows you to visualize flight paths and calculate distances for any route you choose. Click on the MAP option, then type the airport codes in the box like this:

DCA-MIA-EZE (if you were choosing to travel on American via Miami, for example). Or if you use Dulles, it's IAD at the beginning, or Baltimore-Washington, it's BWI, instead of National (DCA).

It looks like going via Newark (DCA-EWR-EZE) gives you the straightest overall line. Other factors have to enter into this too: a schedule that works out for you, airfares, ease of connecting airports, and FF programs. (If you've been using United and earning FF miles, it makes sense to stick with the Newark or Houston flights.)

Bummer! Really not happy to hear this. So I gather from Jeff's post to use UA u have to either fly thru Houston or Newark?

Thank you so much, Jeff, I really appreciate this information and have already put it to use.

Sadly, Yestravel, this is the new United Airlines routing. But there are other options: and to look on the bright side - one can now begin the flight to EZE from DCA or BWI instead of IAD.

I liked the fact that it was a late flight, u could get on, have a bite to eat and then sleep until arrival. Houston isn't too bad, although its been awhile since I flew thru it, but Newark is the pits and has LOTS of delays and travel issues. Have to check how long the flight from Houston to EZE is.

Marnie, is United not going to use Dulles as a hub? Is it scaling back?

jeff, i sure hope not. I have not read that anywhere. Although I think it will e awhile before all the dust settles with the merger. I also saw they are cutting flights to Oakland.
Re EZE - I just looked and the flights from DCA or BWI thru Houston are close to $300 more than the ones that go thru Newark. The thought of flying thru Newark in the winter is not a pleasant one.