Approximate number of U.S. congregations with 2,000+ in weekly attendance:
1970: 10
1980: 50
1990: 500
2005: 1500

Of course this rapid growth of megachurches doesn't mean church attendance has increased. On average 50 small churches close their doors every week in America. We've seen 40 years of the Walmart effect -- consolidation rather than expansion. And while the latest infographic reports the average megachurch was founded in 1971, most were not megachurches in 1971. They were average-sized congregations that reached mega-attendance levels in the 80s or 90s under the leadership of a baby-boomer pastor. (I've profiled a number of such churches in the pages of Leadership Journal over the years.)

With most of these congregations being led by boomers nearing retirement in the next 10-15 years, how will they navigate such a transition? Some will undoubtably be fine. But these are uncharted waters for the young megachurch movement, and churches of all sizes tend to decline sharply during leadership transitions. It's part of the natural lifecycle of an organization. And some never recover at all -- the sad story of the Crystal Cathedral in California comes to mind.

So, while things are looking bright for megas right now, there are serious challenges ahead for these boomer-led churches.

Secondly, the infographic shows that half of all megachurchs (48 percent) are located in young, growing suburbs of a major city. Anyone who has studied church growth or church planting knows that growing communities tend to fuel growing churches. (When was the last time you read about a growing church in Detroit?)

But like pastors, communities also age. I live in suburban Chicago. 30 years ago DuPage county was the growing edge of the Chicagoland area. Numerous churches were planted and grew to mega-status here. But today the growth edge is further west of the Fox River, and since the real estate bubble burst in 2008 growth has slowed significantly.

My point is that a megachurch located in a growing suburb in 1990 may no longer find itself in the same demographic soup that ignited it's rise to mega-ness. Some churches come to this realization and launched satellite campuses to tap into the new growing suburbs, but the long-term sustainability of such a model isn't clear. We're seeing an increasing number of multisite churches, including early pioneers of the model, release their campuses to be independent churches. Colonization, as history has shown, is rarely sustainable.

Adding to the dilemma is the megachurch model of very large facilities. It isn't likely that a megachurch formed in 1985 will abandon it's massive $30 million facility and relocate 40 miles away to be on the growing edge of the city again. They're going to have to find a way to fill and fund their facility in a suburb that is no longer growing demographically. For many that could prove challenging.

Finally, the chart shows that 85 percent of megachurch attenders are white. And I'm guessing that statistic is probably equally true about megachurch leaders as congregations and leadership usually reflect one another. (Sorta the way owners resemble their pets.)

In 2008 the census bureau reported that whites will be a minority in the U.S. by 2042, eight years earlier than last predicted. And that date may accelerate once again depending on immigrant birthrates. And in some parts of the country the date will be much earlier. The point is, if most megachurches remain 85 percent white they will find a shrinking pool of potential members as the population becomes increasingly brown.

Am I predicting the demise of the megachurch movement? By no means. I think these large churches will continue, and we cannot lump all megachurches into the same category. Not all megas were started in 1980 by a baby-boomer in a growing white suburb. And many will navigate into the future with wisdom and skill.

But the cultural and demographic conditions that have fueled much of the megachurch movement, multiplication and growth are changing. And whenever a new movement tries to leap from one generation to the next there are some who don't clear the gap.

I'm reminded of an article by Walter Kallestad in Leadership. Walt led Community Church of Joy in Phoenix, a megachurch that had been an average congregation of 200 before he took over in the 80s and oversaw it's growth. But in 2002 he suffered a massive heart attack requiring six-way bypass surgery. The heart attack, says Walt, was a "wake up call" for the leaders to develop a succession plan to ensure the megachurch continued to thrive after Walt's tenure.

Kallestad began networking around the country looking for a young pastor he could bring onboard and eventually hand the church over to. One conversation stuck with him.

"It's a pretty good opportunity," Walt said. "We have 187 acres just of a major freeway, multipurpose buildings, and a great staff."

The leader looked him in the eyes and said, "Who'd want it? Who in their right minds would want to run that?"

"That's when it dawned on me," Kallestad reflected. "By the time we service the $12-million debt, pay the staff, and maintain the property, we've spent more than a million before we can spend a dime on our mission. At the time, we had plans for a spectacular worship center with a retractable roof. After that conversation, I scrapped it."

As Walt Kallestad discovered, for younger church leaders who value mission, social activism, and innovation, the thought of maintaining the mega-institutions built by their parents generation may prove to be a tough sell. No matter what happens, the next 10-15 years are going to be critical ones for the future of the American megachurch movement.

FOOTNOTE: Only eight TEC dioceses have churches with an ASA of 1000+. Seven dioceses have only one church that size. They are: Alabama, Atlanta, Dallas, Florida, Los Angeles, Indianapolis, and South Carolina. The remaining one TEC diocese -- Texas -- has three congregations of 1000+.