Here's the basic rundown of the NEC, heading north from WUS.
Once clear of the terminal area MP 132 or so, 2 tracks to Landover MP 128, where a third track comes in on the east side of the main. However northbound trains can't access that third track (at least according to the info I have), until they are north of New Carrollton station at Bowie interlocking MP 121. There is also a gauntlet track on the #2 track for south bound freights to clear the east side of the station platform.
North of BWI at Winans MP 103, a fourth track is added on the east side of the main. Four tracks run until Bridge interlocking MP98, just south of the Baltimore tunnels. Only two tracks run from there into the station at Baltimore.
North of BAL MP 95, there are three tracks in the tunnels. Upon emerging from the tunnel it goes up to four tracks at MP 94. That's maintained until Gunpowder River MP79, where the main drops to two tracks. A two track main runs to just north of the Bush River MP 71, where it goes back to three tracks. That runs to Grace MD MP 61, where it drops back to two tracks to cross the Susquehanna River.
Once across the river it increases to a 4 track main through Perryville MD, and then returns to 2 tracks at Prince MP 57. Two tracks run to Bacon MP 51, where a third track returns. At Iron MP 42, a fourth track is added. The 4 track main continues thru the Newark Del station and then drops back to a 3 track main at MP 37.
For a brief stretch between MP 30 & MP 29, it drops to a two track main, but quickly returns to 3 tracks prior to entering Wilmington. Right north of Wilmington at MP 26 the main briefly returns to two tracks for less than a mile.
At MP 25 it returns to a 4 track main, which is maintained into Philly MP 0.
As I mentioned before, north of Philly 4 tracks are maintained at all times to Newark, NJ. There are even a few stretches where it is a 6 track main.
Out of Newark it varies between 2, 3, & 4 tracks over the course of 4 miles. Just past the new Secaucus Junction, the line drops to a 2 track main for the Hudson River Tunnels into Penn.