LOL, that figure is clearly off. That's double the population of the entire state!

Per another comment it's much closer to correct for the annual number of vehicle crossings.

It is between 30-35k/day, about 12.5 million/yr.

One way to assess these numbers is to conduct a quick sanity check. How many cars per minute or second would this be?

11.5 million cars/day is equivalent to :

  ~48,000 cars/hour
   ~8,000 cars/minute
     ~130 cars/second

Clearly, somethings ... a tad off.

11.5 million cars per year however works out to:

  31,000 cars/day
   1,300 cars/hour
      21 cars/minute

Or roughly a 3 second headway per vehicle. Given four traffic lanes (two in each direction), that would be a vehicle every twelve seconds per lane, which seems far more reasonable. That's spread out over the day, so peak-hour traffic would be much higher.

Peak capacity for a highway lane is just shy 2,000 vehicles/hour:

<https://www.mikeontraffic.com/numbers-every-traffic-engineer...>

Which would put the Key Bridge's maximum capacity at about 192,000 vehicles/day.

For comparison, the San Francisco-Oakland Bay Bridge saw about 42.7 million paid toll crossings. As these are metered only in the westbound direction, actual crossings are likely double that, or 85.4 million/year, or about 230,000/day.

(The bridge sees 1/3 the total traffic of all California state-owned bridges.)

<https://mtc.ca.gov/operations/programs-projects/bridges/san-...>