What if Congress, not the states, did the redistricting?

[patzer]

Just a thought experiment. Imagine Congress was responsible for drawing the boundaries of all the 435 seats nationwide, rather than the states. Just how different would the maps be?

The obvious change is that the party which controls Congress would have a big amount of influence (Dems in 2020, Rs in 2010), able to gerrymander even red states if wanted.

The other change though is that individual representatives would have much more influence over what becomes of their seats (no more throwing one representative of your party under the bus a la New Jersey). So there could be some significant differences there. And unpopular representatives might be more likely to be drawn out.

[Skill and Chance]

Depends.  If it passes as a normal law, it would have to overcome a filibuster in the senate and then be signed by the president.  This would make serious gerrymandering impossible most of the time.  Senate Republicans filibuster in 2021, the Republican House and Democratic Senate deadlock in 2011, and Senate Democrats filibuster until Jeffords switches parties in 2001.  The last time there could have been a serious gerrymander under this system would have been the Dems in 1961, and before that, the GOP in 1921.  With this level of gridlock, it's likely there would have been a deal long ago to outsource the process to a commission or follow a series of neutral standards.

However, another possibility to break the gridlock is that it ends up being exempted from the filibuster like budget reconciliation.  This gets more interesting because then a nationwide Dem map actually could have passed in 2021.  Obama still vetoes in 2011, but R's would have a brief window to pass a one-party map in 2001 assuming Jeffords went along with it.  1991 would be a Dem map, 1981 is a Reagan veto, and 1971 is a Nixon veto.  1961 is a Dem map even with the filibuster, but now 1951 would be the last certain GOP map.

Finally, there is a more out-there constitutional argument that the US House has the authority to draw it's own districts independently without going through the standard legislative process.  If that's the case, the House would likely be aggressively redrawn every time it changes hands. 
 

[It’s so Joever]

It would likely be a strong incumbent gerrymander as much as possible, much like CA-2000s but nationally.