  Pure Yang--Mills theory in 2 spacetime dimensions shows exact Casimir
scaling. Thus there are infinitely many string tensions, and this has been
understood as a result of non-propagating gluons in 2 dimensions. From ordinary
symmetry considerations, however, this richness in the spectrum of string
tensions seems mysterious. Conventional wisdom has it that it is the center
symmetry that classifies string tensions, but being finite it cannot explain
infinitely many confining strings. In this note, we resolve this discrepancy
between dynamics and kinematics by pointing out the existence of a
non-invertible 1-form symmetry, which is able to distinguish Wilson loops in
different representations. We speculate on possible implications for
Yang--Mills theories in 3 and 4 dimensions.
