State Partisan Control, 2005-2019

[smoltchanov]

I recommend site

https://www.ourcampaigns.com/

It contains a lot of info about state legislatures, though most detailed usually limited by last 20-25 years period (though there is some more older). And:

https://americanlegislatures.com/

for ideological analysis (since mid-1990th).

[smoltchanov]

Wow, it's insane how close the state legislatures are to 2016. Especially as the democrats are pretty much certain to pick up the legislature this year, and the DFL would have probably won the Minnesota Senate if it had been up.

THIS year it's "Virginia only".... As other legislatures are either solidly Democratic (New Jersey) or solidly Republican (and even with chances of increased Republican majority) -  Louisiana, Mississippi... So - changes are likely, but - not big one...

[smoltchanov]

An interesting measure might be district errosity over time. For example, is this really partisanship at play? Or did perhaps the 2010 cycle produce a bunch of Pub and Dem local maps that push states towards one unified type of government. I suspect the facts might be somewhere in between, after one examines just a handful of legislatures.

I mean, yeah, gerrymandering definitely played a role, and it's pretty likely that at least a few more States (out of, say, WI, MI, PA, NC) would have split legislatures if it weren't for it. Still, gerrymandering has been a thing for several decades, but the rise of unified government at the State level has been a pretty recent development. Besides, this explanation kind of begs the question, since enacting a gerrymander first requires united government.

I guess I should have been more clear,  I mean the rise of deep data gerrymanders, made possible by modern computer programs with electoral data and tools going back centuries. The kind of software the allows one to draw a Republican district that resembles nothing except Donald Kicking Goofy from two democratic counties. And it really doesn't need to be unified control, as shown by NY where the state house map was gerryed to produce a dem supermajority, and state senate map gerryed to produce a republican majority. In this case, the gerry wanted to produce divided govt. If we accept that the deep-data gerry is new, then there is a theory that state reps could win a majority under 'fairer' gerryed lines (whatever that means) drawn by the opposition because they lacked deep data, and then draw deep data lines to reinforce their new majority. But beyond that yes, it does lead to a chicken and egg scenario which is why I suspect Gerry's are working alongside other factors like the polarization demonstrated above and decline of split ticketing. 

We're not really in disagreement then. Still, even if gerrymandering is completely eliminated, I doubt you'll see split legislatures in states like Oklahoma, Tennessee or Alabama again anytime soon.

The same is true for California, Illinois, Massachusetts or Vermont too. In too many states overall results became too predictable, and thus - elections are openly boring...