@ultralinear
I believe that the bulk of public tennis courts in the United States were built between the 1930s and the 1980s. Tennis saw its peak popularity in the US in the 1970s. (Many of the 35+ million players back then were regular players). Participation numbers have dropped off significantly since then… by something 1/4 to 1/3.
In the past decade, the number for tennis has risen slightly, especially since the pandemic. However, higher numbers include a large number of occasional players. The core, frequent players, represent a smaller % of the total.
While tennis participation has increased slightly in the past decade, pickleball participation has increased at a much faster rate. It appears that its numbers have exceeded tennis. The number of regular Pball players is believed to be around
25 million in the US in 2025/2026. If you add in occasional players, that number is about double — around 50 million.