Is the Structural Engineering Profession Growing?

Is the average age of a professional engineering or structural engineering license increasing or decreasing? -- For a healthy growing profession, I would expect to see level or downwards trends for the age of a license, and a linearly increasing number of active licenses at a minimum.

Background

I'm giving a presentation on retention in structural engineering in a few months based on the most recent round of SE3 survey data. Unfortunately, one of the most difficult things about working with this data is that it provides an incomplete picture of the structural engineering industry.

While there were over 5000 respondents to the survey in 2020, this represents only a fraction of professionals practicing structural engineering in the country. California alone has nearly 4400 licensed structural engineers and only had ~1100 responses to the survey; the next closest state was Texas with 300 respondents. I've wanted to look at licensure data for a while as a better metric of whether the profession is growing/shrinking/stagnant.

Anecdotally, 70-80% of the people I've vaguely kept in touch with after graduate school have left structural engineering. Some of the remaining few that are licensed and "practicing" are not traditional consulting engineers (i.e. someone designing a building or bridge and submitting stamped drawings to the city/state). The structural engineering and civil engineering subreddits are littered with dissatisfied engineers contemplating leaving the industry, some of whom have attained a structural engineering license (a step beyond the typical professional engineering license). I also know several people who have their SE license, but they are no longer in practice since they can pay the maintenance fee and keep it in their back pocket in case they come back to the field at a later point in time.

The Licensure Process

But just what does licensure look like for structural engineers today? I've touched on the cost and resources required for the professional engineering (PE exam), but the structural engineering (SE) exam is a much more in depth examination, clocking in at 16 hours (split over 2 days) and testing knowledge of vertical (gravity) and lateral (seismic and wind) design for both bridges and buildings. Depending on the state, this exam may not be recognized any further than the PE exam, and there are very few states that require it to do any type of structural engineering work. Most require it only for special and significant structures.

However, the experience requirements to sit the exam also vary widely. In my state of California, my professional experience essentially reset when I passed my PE exam in California, which means I would need to practice for an additional three years to be eligible to take the exam, whereas in Nevada or Illinois, I'm already eligible to take the SE exam based on my current level of experience. It's a patchwork of requirements that's confusing to navigate and depending on where you settle down may be entirely unnecessary to advance your career.

Finding the Data

Gathering data about PE/SE licensure was largely a mixed bag thanks to a lack of uniformity in state websites/databases. Some states happily provide an up-to-date csv data dump from their databases, while others only allow single license lookup. Others still would email you a csv "roster", for anywhere from $10 to $1000+. The variance in approaches probably has to do with the type of data within these rosters. Some of them get entirely too specific for my purposes (providing emails, phone numbers, and addresses), where I'm really only interested in the following information:

About half the states/territories in the U.S. had csvs or html pages that I could download and parse. Unfortunately, a number of those (like Florida and New York), do not include any information beyond "Professional Engineer" in terms of sub-specialty. I chose to look at Illinois, California, Texas, and Massachusetts for the following reasons.

Results

Licenses Awarded Per Year

The above chart is interactive. Hover over a bar to get precise numbers for active licenses and inactive licenses based on the license year and choose which state to display from the dropdown menu.

The first thing I looked at were the license stats: at what rate are people getting licensed as SEs/PEs, and are the numbers increasing every year (a quick look at graduation statistics revealed that civil engineering rates have increased linearly for the past 20 years). I used a stacked bar chart to show how many licenses are currently inactive for those licensed in a given year.

In California, the number of SEs licensed in a given year is on a downward trend since reaching a peak in 2012. What's more, when the exam was cancelled in Spring of 2020 (it's only offered twice a year currently), the number of licenses awarded in the following year did not indicate a bounce back for test takers that delayed by a year plus those that were planning on testing in 2021 to begin with. California however, does not have a lot of delinquent licenses for "younger" engineers. This is likely due to the fact that once you get an SE license in CA, you do not have to do any continuing education requirements; you just need to pay the biannual license fee.

In Illinois, licensure rates have followed an increasing trend, but the plot does exhibit the same behavior as California where there was no bounce back (> 2x expected new licensees compared to 2020) for test takers delayed by the pandemic. Additionally, there are a lot more delinquent licenses (either "inactive" or "not renewed") among those who've held an SE license for 15 years or less. Illinois does require continuing education credits (a single professional development hour (PDH) can cost hundreds of dollars), so people would be more likely to fail to renew their license rather than hold onto it if contemplating leaving the profession.

For PE licenses, Texas has a strong upward trend with very few lapsed licenses, even though they require 15 hours of continuing education per renewal cycle. Massachusetts has a surprising number of lapsed licenses, and a similar proportion to Illinois in terms of recent (within the past 15 years) licensees.

Cumulative Number of Licensed Professionals and Average "Age" of a License

The above chart is interactive. Hover over the line to get the average age of a license in a given year, or hover over a bar to get the precise number of active licensed professionals in a given year.

Plotting the cumulative number of active licenses as well as the age of a license showed some interesting trends. As I suspected in California, the "age" of a license has been increasing with nearly the same slope since the 90s (aside from a brief leveling off around 2010) and is now 20 years old. In Illinois, the license age has been holding steady around 15 years since 2000. In Massachusetts and Texas, the age has also been approaching a steady value, though licenses in Massachusetts (18 years) are about 4 years older than those in Texas.

For active licensed professionals, all states other than Texas show signs of leveling off, though this is particularly pronounced in Massachusetts, where the number of active licensed PEs has hovered around 2400 for the past 20 years.

For a healthy growing profession, I would expect to see level or downward trends for the age of a license, and a linearly increasing number of active licenses (this is assuming that graduation rates for the field are continuing to grow linearly as previously mentioned), but this does not appear to be the case for anywhere other than Texas.

Historical Distribution of Years of Experience Among Active and Delinquent Licenses

The above charts are interactive. You can choose the state and year of interest to see the distribution of years of experience or years of experience before exiting the profession as a histogram.

For the sake of completion, I also broke out the distribution of years in practice (the average value plotted as a line in the previous plot). For some states, this showed that for licenses issued prior to 1990, essentially zero engineers let their licenses lapse (but that could also be a symptom of bad recordkeeping) and were active in the profession for 30+ years before exiting practice.

For California, this showed the bimodal distribution of years of experience for SEs as of 2021. In Massachusetts, these plots potentially indicate that the greatest number of exits from the profession occur in the first 15 years within that state.

So What's the Point?

I'm not going to do an in-depth statistical analysis of this data, because I don't have all data (and I'm not going to pay thousands of dollars for it). However, this exercise confirmed some of my suspicions. Based on what I've seen, I can't say that there are a growing number of people in my generation attaining the highest level of SE licensure and leaving the profession (despite what appears on reddit), but I can say that it does seem like fewer people are getting an SE license and those that do are not necessarily holding onto it.

The profession appears to be growing older as well, and I don't think additional gate-keeping with more certifications and required education or exams (as suggested by the Vision for the Future of Structural Engineering Licensure Report) is going to bolster the numbers anytime soon.