Analysis
NAICS 4851 is the 2022 industry group for urban transit systems, part of 485 (Transit and Ground Passenger Transportation).
It has only one more detailed code, 48511, which covers exactly the same activities; the definition, index entries and statistics are on that page.
Between 2018 and 2023 the number of establishments fell 17% and employment fell 14%. The 2018 count used NAICS 2017, so part of a large move can come from codes being redefined rather than from businesses opening or closing.
County Business Patterns counts 618 US establishments in this code in 2023, employing 47,318 people at an average annual payroll of $64,565 per employee (42nd percentile of national industries). 33% of the establishments have fewer than five employees, which is close to the national mix.
By establishments it ranks 5th of the 6 codes at this level within Transit and Ground Passenger Transportation, with 3% of them.