Before talking about national transit trends, it’s important to grasp the relative size of the NYC market. The chart below shows the top 10 transit agencies by monthly ridership (June 2019 unlinked trips). NYC dwarfs the other transit markets, and for this post, is set aside as an outlier.
So what’s going on outside of NYC? Here is the raw data of transit ridership over time by agency. We’ll need to do some further processing before any useful information can be extracted.
Collapsing Agencies
A histogram of June 2019 ridership tells us that there are a few agencies between 10 and 40 million monthly trips, several between 2 and 10 million, and then the large majority of agencies are below 2 million monthly trips.
To make the time series charts more legible, we’ll collapse agencies under 2 million into a single agency and display their median ridership. We’ll create another median agency representing agencies between 2 and 10 million.
Seasonality
Understanding transit ridership is also complicated by the seasonal nature of it. For most agencies, ridership is low in December and January and peaks around October. Removing these seasonal variations helps us understand the underlying trends. The chart below shows the monthly ridership for the Chicago Transit Authority. The actual ridership is shown by the jagged line while the trend is highlighted in orange. The trend line makes it clear that (seasonally adjusted) ridership peaked in April of 2012. As a point of reference, the vertical green line marks when Uber began service in Chicago.
Results
With the above modifications in place, the chart below tells a fairly concise story about what is happening to transit ridership. Medium markets like Chicago began seeing declines in ridership between 2012 and 2014, and this trend has has continued. This is the same time frame when Uber and Lyft began showing up in these cities. While not enough to say that these companies caused the decline, it is certainly interesting.
The small (<10 million) and tiny (<2 million) agencies look relatively stable in the chart above, but that is mainly due to the scale of the graph. The charts below zoom in to provide a more accurate picture. The median ridership in these markets is also falling. The decline in the tiny markets starts noticeably later. One theory could be that Uber/Lyft simply arrived in these regions later.
The Uber/Lyft connection seems obvious, but this post has not done the work required to say anything for sure. In a future post, I hope to look at the link in more detail. The goal of this post was primarily to provide insight into what is happening with transit ridership.
Reproducibility
Reproduce what you see above and take it further! If you do, send me a link and I’ll post it here. Everything you need to get started is on GitHub:
Data: FTA xlsx (original source is always the latest month)
Code: Rmd
