The consolidation of San Antonio and Austin into a single statistical “megaregion” offers some obvious appeal to civic boosters and those concerned about future economic growth. While San Antonio’s national profile has increased in recent years, we are realistically the fourth city that comes to mind when most outsiders think of Texas.

San Antonio is actually larger than Austin in metropolitan population, but we still rank only either 25th or 29th among regions nationally, depending upon the metric. A combination of San Antonio and Austin, on the other hand, would today rank 15th and could be among the Top 10 by 2050 based on a continuation of current growth rates.

From a national and global perspective, a region comprising five or six million people in the next decade or so would attract more attention and opportunities than two separate regions of two or three million each. In one case, we’re in the same league as Seattle or Atlanta; in the other case we stack up against Indianapolis or Cincinnati.

It is easy to imagine the benefits that could result from a melding of the two cities into a single integrated region – with more corporate headquarters, international business, air travel, and professional sport franchise options among a few of the more obvious ones.

It also is easy to assume this future is more or less inevitable when one observes the nearly uninterrupted commercial development along IH-35 between San Antonio and Austin or notices the presence of both cities and the counties in between, in the rankings of the fastest growing places in America.

Intrigued by the impact this greater regional identity could have on the future of San Antonio, I set out to examine the question of how close a San Antonio-Austin megaregion is to becoming a reality.

Google images compare the Austin-San Antonio region to others across the country. Rendering by Karl Baker via Google Earth.

While measuring metropolitan or regional identity is an inexact science, the Census Bureau has developed the most widely accepted and cited system for categorizing metropolitan regions.

For the purpose of this discussion, the two relevant categories used by the Census Bureau are Metropolitan Statistical Areas (MSA) and Combined Statistical Areas (CSA). MSAs are defined as counties with a “high degree of social and economic integration (as measured by commuting to work) with the urban core.” The MSA for San Antonio, for example, comprises Bexar County (the urban core) and the seven surrounding counties.

CSAs, on the other hand, are often agglomerations of two or more MSAs that have a degree of social and economic integration, but not as much as in an MSA. For example, while San Francisco and San Jose each comprise separate MSAs, they are part of a single CSA – the “San Jose-San Francisco-Oakland, Calif. Combined Statistical Area” – which ranks fifth nationally in population.

One way, then, of answering the question of how close a San Antonio-Austin megaregion is to becoming a reality is to answer the question of how close they are to becoming a single CSA. Contrary to my expectations, it turns out that the answer to this question is: not very close at all.

Some additional explanation of the data and methodology used to arrive at this conclusion is set out at the end of this article. As a general matter, however, the data shows that the level of interaction between Austin and San Antonio needs to increase more than 500% from the current level reflected by the most recent data before we could start referring to a San Antonio-Austin CSA.

While one might expect this gap to close along with the rapid growth in Hays, Comal, and Guadalupe counties, some statistical projections, which also are explained below, suggest that the current growth in those areas will not move the needle significantly. Moreover, an argument also can be made that the core areas of San Antonio and Austin are actually growing further apart due to the increasing congestion along IH-35.

For example, if a typical daytime trip between downtown Austin and downtown San Antonio ends up taking two-and-a-half hours – not unheard of these days and certainly possible in the future with all the growth along the corridor – then it almost makes as much sense to talk about a Houston-San Antonio CSA as it does to talk about one for San Antonio and Austin.

Despite these sobering statistics and realities, I still believe it is important for San Antonio’s future to plan for greater integration with Austin, and I hope to see this become a reality. While the 74 miles between the centers of the cities are certainly an obstacle to overcome, technology exists today that would permit San Antonio and Austin to function more as an integrated region by way of commuter rail, for instance. Additionally, advances in technology, including those already underway – think driverless cars – should make this even more feasible in the future.

Moreover, I think the benefits that could accrue from succeeding at this endeavor are extraordinary. Done right, it is not hard to imagine two unique cities sharing world-class amenities and a dynamic economy, interconnected by a transportation system that allows residents and visitors to experience the best of San Antonio, the best of Austin, and the best of the Hill County as part of a daily or weekly routine.

An identifiable Austin-San Antonio region also would be a place literally and figuratively on the map in ways that the two separate cities would not. While Austin and San Antonio can both claim to be great cities with a lot to offer individually, together they have the potential to form one of the most dynamic and culturally rich regions in the United States. Perhaps, even the first place people think of when they think of Texas.

Grasping this future is not only a challenge, but it seems very unlikely to happen by accident. Rather, it will require deliberate, thoughtful, and bold action by community leaders to lay the groundwork for this integration, and progress will be seen over decades, not years.

Explanation of Data Cited Above

A statistics mechanism called the “Employment Interchange Measure” is used to determine whether two MSAs should be part of a single CSA. The “Employment Interchange Measure” is determined as “the sum of the percentage of employed residents of the smaller entity who work in the larger entity and the percentage of the employment in the smaller entity that is accounted for by workers who reside in the larger entity.” Adjacent MSAs are made part of a CSA when the Employment Interchange Measure between the two areas exceeds 15%. Further information on these concepts can be found here.

The most recent data regarding commuting between counties is from 2006-2010 and can be found here. By aggregating the available data for the various counties comprising the Austin and San Antonio MSAs, I calculated an Employment Interchange Measure of 2.5% for a hypothetical San Antonio-Austin CSA. This figure equals the percentage of total workers residing in the Austin MSA, the smaller entity, that work in the San Antonio MSA (0.88%) plus the percentage of total workers employed in the Austin MSA that reside in the San Antonio MSA (1.62%).

In order to roughly estimate the potential impact of growth along the IH-35 corridor since 2006-2010, I multiplied the commuting data from 2006-2010 for each county in the San Antonio and Austin MSAs by the estimated population growth rate for each such county between 2010 and 2015, thus, making an attempt to capture the impact of the rapid growth in Hays, Comal, and Guadalupe counties. Surprisingly, this made little difference with the Employment Interchange Measure which remained stuck at 2.5% even if these growth rates were assumed to continue through 2020.

The lack of projected change seems due to the influence of rapid growth in all portions of the Austin MSA, including areas that do not have a high interchange with the San Antonio MSA like Williamson County. This means that under the assumed growth rates, the percentage of workers employed in the Austin MSA that reside in the San Antonio MSA actually declines, despite a significant increase in the raw numbers of those commuting to the Austin MSA from the San Antonio MSA.

Top image: A yield sign is posted near the High 281 North to Loop 1604 interchange. Photo by Scott Ball.

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