The US Census Bureau will release the results of its 2010 census this summer, and marketers should prepare for some major demographic shifts. After reading a recent interview with Peter Francese, consultant to advertising megalith Ogilvy & Mather and author of the research report 2010 America, I was surprised to learn the following:

There is no more "Average American." Fifty years ago, the concept of John Doe, an average American in a relatively even society where vast numbers of people had similar consumer needs, was real. A societal uniformity existed that has not been equaled since. The 2010 census results will put a nail in that coffin.

We are a true multicultural nation. In the nation's two largest states—California and Texas—no race or ethnicity comprises a majority of the population anymore. In fact, no segment forms a majority in our 10 largest cities.

Family life is diversifying. Twenty-five years ago, two-thirds of all households consisted of married couples. The 2010 census will show that for the first time in American history, married couples will be a minority in the US. The number of people living alone is growing rapidly.

We have become a multigenerational society. Average life spans have significantly increased. With more people living longer than in previous generations, there are greater numbers of multigenerational households than we've seen in recent history. That means older people (age 60+) are living with their children or grandchildren and have a bigger impact than ever before on what those younger generations are buying.

What these changes mean for your marketing is obvious: One-size-fits-all messaging isn't going to cut it. It will seem wildly off-base and irrelevant, especially if you attempt it in your email and social media marketing—avenues in which instantaneous feedback and listening is expected.

So, especially in your online messaging, I recommend adopting three approaches to creating a new relevancy mindset for your email, mobile, and social marketing programs.

1. Demographic segmentation matters and should be tested

That means investing more time and money in database building and management so you can segment by important demographic criteria, such as age, gender, location, household composition, marital/family status, and ethnicity.

Any life-stage marketer can attest to the vastly different consumer needs of new parents, new movers, families with children, and empty-nesters. By not targeting those segments specifically, you're missing huge opportunities to make timely offers to each and reap the benefits of relevant, engaging, and useful messaging that speaks to them "where they live."

2. Recognize, identify, and reach influencers

Marketing isn't a straight line between brands and buyers—influencers play a role, and never more so than today. Social networking makes getting group opinions and feedback easier and more far-reaching than ever. No longer are influencers limited to immediate family and friend circles. Total strangers can become trusted, credible sources of information that influence purchase decisions—positively or negatively—in much more accelerated and mysteries ways than before.

The upshot? Your target market isn't the only group that needs your messages. Remember the influencers, and reach out to them.

3. Don't assume: Analyze and ask instead

For decades, profiling and clustering systems have made predictions and assumptions to classify customers or prospects into similar groups for marketing segmentation. Such systems use demographic and marketing data points to categorize customers or prospects into distinct groups that supposedly fit a certain lifestyle or behavioral profile.

Though useful, these segmentation systems have two shortcomings:

1. Because of the diversifying population, cluster system categories are becoming more numerous and granular, resulting in more groups with fewer members and sometimes too many segments to meaningfully execute to.
   
2. People fit into more than one cluster, sometimes seemingly contradictory ones. The bottom line is that such systems are less effective at profiling database members than those individuals' own stated preferences and demonstrated behavior. So, use online surveys often, continually asking list members what they like, dislike, want to hear about, etc. Then watch their response behavior for confirmation of their stated opinions and intentions, because actions speak loudest; so model future marketing approaches on what your target audience has responded to in the past.

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Until you dig deep into your customer data—demographics, offer responses, media preferences, survey answers, and more—you may have assumptions about your customers that are entirely untrue. Your customers are probably a far more diverse group than you imagined, and unique segments deserve unique treatment. Make it standard practice to revisit your segmentation methods and reassign individuals to new segments as their behaviors—or demographics (e.g., age)—change.

Continually rebalancing how and whether you can group customers into like segments increases your ability for super-specific marketing that resonates, engages, and maximizes response. Market to "the average," and you're marketing to a myth. Instead, get to know who your customers really are, and be prepared to invest the time and resources needed to connect with them individually.

The companies that do so already have a clear competitive advantage in a diversifying America.