DCA went thru a major redesign.

they now have closed off the “ mall” area to now being behind security.

they also converted commuter airplane gate 35X to a new concourse . They renamed the new one E, then C is now D, B/C is now C.

Now they have a north and south TSA for B-E called terminal 2. A is terminal 1 with it’s own TSA.

there is no longer a shuttle bus between concourses B/C ( now C to C ( now D) since there isn’t a security crèche point blocking things.

therr is still some interbbalwork being completed such as removing the escalators/stairs you would have taken from airline check in to the mall area.

the end of concourse E is where the smaller “crop duster” planes will be located ( CRJ, E-175, etc.).

For connection time on American. The old “ mall” does not have moving walkways. The new portion of it extending from D to E does have them. Just by my own estimate if you came in at the end of E and had to get to The end of C it will take about 20 min without running. Add an additional 5 min if you are connecting with Alaska. I don’t know if there are planes for Alaska to move from B to the AA concourses. JetBlue currently is in C.