Obama has decimated the Democratic Party

[muon2]

One thing unsaid in the article is the part of the core Dem appeal. It has shifted over the last 50 years from a labor-based appeal to an urban-based appeal. That contributes to the over-concentration problem since their historical labor votes could be found in every area, but small towns and rural areas aren't going to have a lot of pro-urban voters.

Interestingly the IL Dems have maintained a more labor-oriented message and still hold many local offices downstate, even though the Congressional seats go Pub. That has meant a lot of political work to balance competing interests between Chicago and the rest of the state, but that balance has paid off with continued supermajorities in the legislature despite the 2014 results nationwide.

[muon2]

One thing unsaid in the article is the part of the core Dem appeal. It has shifted over the last 50 years from a labor-based appeal to an urban-based appeal. That contributes to the over-concentration problem since their historical labor votes could be found in every area, but small towns and rural areas aren't going to have a lot of pro-urban voters.

Interestingly the IL Dems have maintained a more labor-oriented message and still hold many local offices downstate, even though the Congressional seats go Pub. That has meant a lot of political work to balance competing interests between Chicago and the rest of the state, but that balance has paid off with continued supermajorities in the legislature despite the 2014 results nationwide.

The Illinois senate and assembly is heavily gerrymandered in favor of Democrats.

https://en.wikipedia.org/wiki/Illinois_House_of_Representatives_elections,_2014

Despite a 1% margin for the GOP. The dems got 60% of seats.

The Dems also hold a number of significantly Pub seats in downstate IL. Gerrymandering helps, but so does a message that keeps voters Dem in these more local contests.

[muon2]

A century ago the Senate was effectively chosen by State legislatures and no better than those legislatures.  The Seventeenth Amendment made the Senate electable by the People of the States, thus ensuring that the Upper House was democratically elected. Now the State legislatures mostly have effective control of the content of the state delegations to the House of Representatives through control of the boundaries of districts.

The trick is to concede a few districts to the "wrong" Party and dilute the rest.  Republicans can thus ensure that small cities that might vote "wrong" are diluted in a rural hinterland that votes "right". If at the opportune time the State legislature goes one way it can entrench Congressional representatives of its choosing.

Even worse is that state legislatures get to chose the state level districts as well.  I.e. they can gerrymander themselves in place.  The only way Democrats have to break this cycle is to win Governorships.

States where the governor has veto power over redistricting, there are multiple districts to draw, and districts aren't drawn by commission:
2015: KY, LA
2016: MO, IN, WV, NH, UT, OR
2017: VA, NJ
2018: HI, NV, NM, CO, TX, OK, KS, NE, AR, IA, MN, IL, WI, TN, AL, GA, SC, OH, MI, PA, NY, MA, RI, ME

Color (not Atlas colors, sorry) is which party currently holds office, bolded states are what I think Democrats should focus on taking/holding.  

The legislature does not draw the maps in IA. They are drawn by an independent body according to statutory rules. The legislature is given an up or down vote on the plan (congressional and legislative) and if rejected can specify specific goals from statute that should be addressed then try again. Gerrymandering is not an issue there.