United States Intercity Bus-Market Size
While there is no publicly available information to fully answer your question, we've used the available data to pull together key findings: Based on the US revenue for the overwhelmingly dominant players, Greyhound and Stagecoach, we triangulate that the US Intercity Bus segment of the Scheduled and Charter Bus Services Industry to be worth approximately $1.71 billion in 2018. Below you'll find an outline of our research methodology to better understand our findings and the necessary calculations to arrive at this figure.
INITIAL RESEARCH FINDINGS
We began our research with an attempt to find existing market research reports. While such reports are proprietary and often expensive to obtain, it is very common for them to provide the market size and some additional information in the public summaries. In this case, we were unable to find a report that perfectly fit the report criteria, but did find some valuable information which helped to frame and verify our ultimate conclusion.
According to the summary page for a for-pay market report by IBISWorld, the total revenue for the US Scheduled and Charter Bus Services Industry — which includes but is not limited to intercity transportation — was about $5 billion in 2018. Unfortunately, the breakdown by segment which would have let us determine the answer of the question as given was not available in the summary, though an unlabeled chart suggests that the Intercity segment could be, at a maximum, about two-fifths of that. This gave us an upper bound which served as a guidepost for the rest of our research.
Note: Due to the way IBISWorld handles incoming links, the above inline citations may redirect to the site's homepage instead of the report. Screenshots of the data have been included in the attached document and if needed, the following direct URL may be used instead: https://www.ibisworld.com/industry-trends/market-research-reports/transportation-warehousing/transit-ground-passenger/scheduled-charter-bus-services.html
Our second discovery was a report from the DePaul College of Liberal Arts and Social Sciences entitled, "New Directions: 2019 Outlook for the Intercity Bus Industry in the United States." While this report was extremely detailed and provided valuable context, to our surprise it did not provide any revenue figures for the industry as a whole. It did, however, provide the names of some major players in the market and, in some cases, links to their annual reports.
We found it telling that even a report specializing in this very segment did not provide the market size, leading us to hypothesize that, perhaps due to the number of small players, is not widely known. Nevertheless, we branched our research to include official government sources, particularly the US Department of Transportation and the Bureau of Labor Statistics. The former provided one report with some relevant data, but as it dated to 2005, we deemed it too old to be useful and so was not cited. A search of Google's scholar database likewise found no salient data, as the few academic works on the subject were more interested in either measuring intercity bus travel by road miles than dollars or in measuring the impact of government spending in this sector. Again, as these are not relevant, we have not cited them below.
Next we studied the annual reports of the largest players to see if either contained an estimate of the total market, but this proved not to be (though said reports proved instrumental in our ultimate triangulation; see below). Finally, we conducted a broad search of trusted news sources, both business-oriented (e.g., Forbes, Business Insider) and general interest (e.g., the New York Times, the Washington Post, US News and World Report), but found no articles with the needed information.
THE MAJOR PLAYERS
Since the size of the US Intercity Bus segment does not seem to be in the public domain, the next natural step was to attempt to triangulate it from the available data about the major players in the aforementioned "New Directions" report, including Greyhound (owned by FirstGroup), Stagecoach (owner of Megabus and Coach USA), RedCoach, FlixBus, OurBus, Vonlane, BestBus, Catskill Carriage, Trailways of New York, Concord Coach Lines, and Washington Delux. It also gave us the names of several of the lesser players, like Limoliner, Tripper, and Vamoose, many of which operate only in specific regions or even states.
We then attempted to pull the revenue figures for each, using their own annual reports wherever possible. This gave us the following figures for the two largest companies, which are also the only two publicly-traded companies:
Greyhound - $912.7 million
Stagecoach - £470.9 million
Both of these revenue figures were for the North American market, not just the US, which will be taken into account in the ultimate triangulation.
We found that none of the other companies listed as "main players" in the report even came close to the big two, and several were set aside on other considerations. For a few representative examples: We found that Flixbus is a German company which has only just reached the US and which has only $48 million in annual revenue, and so we judged it to be inconsequential to the US market. OurBus proved to be a startup "travel and transportation platform" rather than a bus company, and so was also removed from the list. Vonlane operates only in Texas and only reached the $10 million mark in 2017, which proved to be about average for the smaller players whose revenue we could locate. (Note that as it ultimately did not factor into our calculations and to keep a clean source list, we have not attempted to document the revenue of every smaller player.) Finally, in many cases, like RedCoach and BestBus, the companies were so small that they did not appear in company data repositories like D&B Hoovers or Buzzfile, indicating that they must be very small indeed.
ASSUMPTIONS AND CALCULATIONS
Ultimately, the sheer number of small bus companies and the lack of credible public sources for their current revenue meant that attempting to track every small company would be an exercise in futility. However, since our research was conclusive that Greyhound and Stagecoach were the two largest players by an enormous margin, we can triangulate the US market by applying the 80-20 rule, aka the Pareto principle. As explained by Investopedia, "80% of outcomes (outputs) come from 20% of causes (inputs)." In this case, we would expect 80% of the Intercity Bus market segment to come from the companies in the top 20% of the market; in this case, from Greyhound and Stagecoach.
While the Pareto principle is only a general principle and the fragmentation of the market might result in us, if anything, underestimating its size, given the dearth of information available in the public domain, this provides us with the best estimate possible of the US Intercity Bus market.
We next converted Stagecoach's revenue to US Dollars. At current exchange rates, Stagecoach's £470.9 million North American revenue equals $612.5 million. Since we could find no public source that directly provides Canada's share of the North American Intercity Bus market, we triangulated the US share via a ratio of the two nations' populations using the following formula: 331.2 million [US] / (331.2 million [US] + 37.4 million [Canada]) = 89.9%
Therefore, after adding the revenues for Greyhound ($912.7 million) and Stagecoach ($612.5 million) to arrive at $1,525.2 million, we multiplied this by the US share of the North American population (89.9%) to arrive at US revenue of $1,371.2 million. If this indeed represents 80% of the US market, then the total US Intercity Bus market in 2018 would be approximately $1,713.9 million (1,371.2 / 0.8). This accords perfectly with our earlier observation from the IBISWorld report that the Intercity segment could be no more than two-fifths of the $5 billion Scheduled and Charter Bus Services Industry; that is, it must be equal to or under $2 billion.
Based on the above, we triangulate the US Intercity Bus market at approximately $1.71 billion in 2018. While IBISWorld indicates that the bus transportation industry, in general, is experiencing 0.9% annual growth (CAGR), we cannot say that this is true of the Intercity segment in particular based on the extant data in the public domain.