Demographic Change and Same Sex Marriage in Colorado

Using the results of Amendment 43 as indicating the proportion of opposition to gay marriage (56% to 44%) then using demographics it can be determined approximately when a majority will support the amendment’s repeal.

To do this I first use the report P20-556 by Kelly Holder of the U.S. Census Bureau studying the characteristics of the voting population. From it I approximate the voting population in Colorado as 9% of voters are age 18-24, 14% are 25-34, 19% are 35-44, 21% are 45-54, and 19% are over 65. This, of course, carries the risk that Colorado’s voting demographics are different due to our younger population.

According to the paper “Explaining Rising Support for Same-Sex Marriage in California” by Gregory Lewis of Georgia State University and Charles Gossett of California State Polytechnic University, Pomona almost all of the change in support for same sex marriage since 1997 is caused by cohort change. That is one generation dying off and new ones coming of age. They found this by studying the data of the Field Poll of Californians about the subject, which had been repeated six times since 1985 at the time of their study.

From an article the Sacramento Bee on most recent Field Poll in California I got the data for the most recent poll done this year. It found 68% of voters 18-29 years old said they favored allowing same-sex marriage. 58% of voters 30 to 39 and 51% of voters 40-49 favored gay marriage. That compared with 47% of voters 50-64 and 36% of those over 65 who supported the idea.

Now I do some back of the envelope estimations on Colorado’s population as of 2006. I estimated 69% support by those under 18 years of age, 67% for 18-24, 57% for 25-34, 50% for 35-44, 46% for 45-55, 35% for 54-65, and 27% for those over age 65.  I got these percentages by using the actual vote in 2006 on Amendment 43, 855,126 against gay marriage and 699,030 for it, and then running that through my age cohorts with percentages until the numbers balanced (after rounding).

Then I started replacing age groups with younger ones with two-year intervals in my spreadsheet. (How I love spreadsheets!) From this I found that the break over point using these assumptions comes in election year 2014 when a very small majority supported gay marriage. I would guess to take Amendment 43 out of the constitution will take a few years beyond that, though.

My numbers gets to about 54% for to 46% against in 2020, twelve years from now, so I would guess that would be the safe date for a referendum or initiative given the random fluctuations of public opinion. I then ran this in a different way. My second run found a very, very slightly higher percentage for gay marriage, in no case was it more than 0.5%. The reason for this is that the first run each subsequent set of numbers depended upon the previous election cycles set.  That meant rather than being exactly 69% for the youngest cohort in 2016 it was instead 68.6281311%. I knew this would happen and figured it would just make my numbers a bit more modest, so I’m inclined to go with my first run.

So my guess is that gay marriage will be legalized in Colorado in about six years at the very soonest and twelve years at the latest.

Estimate of numbers Against and For Same Sex Marriage:


53.6% Against

46.4% For


52.2% Against

47.8% For


50.8% Against

49.2% For


50.5% For

49.5% Against


51.8% For

48.2% Against


53.0% For

47.0% Against


54.2% For

45.8% Against

7 Community Comments, Facebook Comments

  1. One Queer Dude says:

       There’s one more twist to put into your analysis:  would it be better to put the repeal initiative on the ballot in a presidential year or a gubernatorial year?

      Assuming that younger voters are more likely to vote in presidential years than off years (and conversely, older people vote all the time), my guess is that it would be better to run the repeal initiative in a presidential year.

    • Precinct854 says:

      That makes sense. I did not correct for that, though that could mean that the numbers are more gay friendly than I assumed since the starting numbers are from a gubernatorial election year.  

      Though we might also assume that there are 1-2% who vote no on all ballot questions, so it might be harder to get this out than my numbers assume.

      The two effects might cancel each other out at least in presidential years. And it would (of course) depend upon enthusiasm and turn out. Someone like Andrew Romanoff running for Gov in 2014 or 2018 could make the youth turn out a lot better than the usual midterm election.


    • Precinct854 says:

      Running it again assuming there were less young voters in 2006 actually improves the numbers very slightly after 2014 and worsens them before then very slightly.  This is because then I have to assume that even more people in the 18-34 age group support gay marriage. Otherwise I need to assume that old voters are more supportive and the numbers don’t actually change very much.


  2. DavidThi808 says:

    My daughters all have friends who are gay – to them it’s just a normal thing in life. They can’t understand why anyone would oppose it.

    It’s coming, and it’s coming soon. My guess is the state Supreme Court here will find the no gay marriage amendment unconstitutional sometime in the next 6 years, and then the legislature will make it legal.

    • Precinct854 says:

      I’m not so sure about the courts. Given the fact that it was voted in as an amendment to the state constitution they would have to find that under the federal constitution there was an equal protection problem, unless I’m mistaken. And that would bring the Feds into it and I’m pretty sure they’d rule against marriage being an equal protection issue given the current composition of the court. And the courts tend to be slow with something they don’t like. I would guess constitutional amendment via direct initiative in 10 years if the polls are favorable or twelve if it is at all close.

      If it came sooner I would expect it would be because with it moving through other states the polls here might swing the other way an encourage a ballot question to take 43 out in eight years or even six. But surely not before then.


      • One Queer Dude says:

        …and the state Supreme Court did not let that stand in the way of doing the right thing.

          Those activist judge…you’ve got to love them!  (Especially since some of the best ones have been Republican appointees!)

        • Precinct854 says:

          I can think of a number of things that may make Amendment 43 different than Amendment 2. First off Amendment 2 was changing current state law and overruling municipalities. Trying to overrule Amendment 43 would have to go the other way and overturn current practice and law, which courts will be slower to act upon than preventing something novel.

          As fast as things happened with Amendment 2 it was three and a half years from the passage to it being decided in the Supreme Court. So that sets a minimal time for such action, I think. If a couple got married in California today and came back to initiate a case I would expect the final decision not to come for at least four years, if not five or six. In Connecticut the legal fight has already gone on for four years just at the state level.

          Then we come to the Federal Courts. If the lawsuit was under equal protection and the 14th provided by the US Constitution I would expect that it would go to them eventually. And with the current composition of the court I would not be absolutely confident of winning.  Kennedy joined by Stevens, O’Connor, Souter, Ginsburg, and Breyer ruled against 2. O’Connor is gone and Kennedy specifically wrote in Lawrence v. Texas that the case did not involve whether the government must give formal recognition to any relationship that homosexual persons seek to enter.

          Unless one of the conservative justices dies and Obama appoints a new one I think the case from first suit to last decision would take five to six years and end in a loss.

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