Does anyone have a blank map of the 1976 congressional districts?

[muon2]

This map looks more reasonable and less gerrymandered.

Many of those districts are gerrymandered, just not to the extreme shapes we see today. The reason is computers.

Computers and their databases were just moving into the corporate world; one of my college classmates interned with a company to help interpret customer usage data, since no one on staff understood it. Government officials were even less familiar with computers except as tools for the defense and space industries. GIS was in its infancy and was primarily an academic endeavor.

As computers and GIS became more powerful and more accessible to political staffs, the ability to line up political results and demographic groups became easier. That allowed partisan interest to sculpt districts with more precision to get specific results. Those districts are more obviously gerrymandered to look at then these from the 1970s.

[muon2]

This map looks more reasonable and less gerrymandered.

Many of those districts are gerrymandered, just not to the extreme shapes we see today. The reason is computers.

Computers and their databases were just moving into the corporate world; one of my college classmates interned with a company to help interpret customer usage data, since no one on staff understood it. Government officials were even less familiar with computers except as tools for the defense and space industries. GIS was in its infancy and was primarily an academic endeavor.

As computers and GIS became more powerful and more accessible to political staffs, the ability to line up political results and demographic groups became easier. That allowed partisan interest to sculpt districts with more precision to get specific results. Those districts are more obviously gerrymandered to look at then these from the 1970s.

Could you give some examples of gerrymanders on that map?

Cite P. Squire, "Results of Partisan Redistricting in Seven U.S. States During the 1970's", Legislative Studies Quarterly, May 1985:

The paper studied seven states: AL, AZ, CO, FL, IA, NY, and TN where there were changes in the number of districts and one party controlled the process attempting to gain an advantage. The study found,

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The study found that AL and FL were most successful in wining more seats than they would be expected to win based on the way the map was drawn - they won 100% of their targeted seats. The other states were more subject to national tides that largely washed out their advantage by the end of the decade or for Pubs in the wave election of 1974.

One measure, still used today is the number of seat wins by a party compared to the number of votes cast for that party. The FL Dems were able to win 71% of the seats on 55% of the votes. On the other side AZ Pubs were able to win 60% of the seats with 49% of the vote, which was regarded as a significant success for their partisan plan.

[muon2]

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This stat doesn't prove much of anything.  Republicans are more likely to control redistricting in conservative states and vice versa.  

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This isn't definitive; geographic clustering could be a cause as well.

To give a more direct answer to Al's question, the KY district linking Cincinnati and Louisville suburbs, the TN district linking Memphis and Nashville suburbs, and the MO districts which carve up the St. Louis suburbs all look gerrymander-ish to me.  

At that time control was not necessarily about liberal and conservative. Southern states were conservative, but controlled by Dems. NY was known for liberal Pubs. The author identified districts intended to be won by the controlling party based on metrics available at that time (eg. PVI didn't exist). I'd invite you to read the whole article. Gerrymandering doesn't have to look bad to be effective.

[muon2]

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This stat doesn't prove much of anything.  Republicans are more likely to control redistricting in conservative states and vice versa.  

You must be logged in to read this quote.

This isn't definitive; geographic clustering could be a cause as well.

To give a more direct answer to Al's question, the KY district linking Cincinnati and Louisville suburbs, the TN district linking Memphis and Nashville suburbs, and the MO districts which carve up the St. Louis suburbs all look gerrymander-ish to me.  

At that time control was not necessarily about liberal and conservative. Southern states were conservative, but controlled by Dems. NY was known for liberal Pubs. The author identified districts intended to be won by the controlling party based on metrics available at that time (eg. PVI didn't exist). I'd invite you to read the whole article. Gerrymandering doesn't have to look bad to be effective.

PVI is more of a concept than a technology.
There was never anything there to prevent map drawers from effectively calculating what was the same thing as PVI back then if they were willing to spend the time.

The concept of PVI was pretty alien in 1976 (I was taking a college course in presidential elections that fall). Also the idea of using a lot of calculation to maximize congressional gains was also largely unheard of. Typically the parties used county and big city results to make reasonable guesses as to how to protect as many seats as possible. There wasn't any science in it to speak of.