I am saddened to see Stranger on a Train’s otherwise excellent writeup repeat the discredited canard that the Tacoma Narrows Bridge failure was due to resonance. Ignorance must be fought wherever it is found.
IANA bridge failure mechanics expert, but hereis a reasonably succinct summary of the two different modes (vertical harmonic driven by vortex shedding and torsional flutter) probably involved in the failure. The article is now fifteen years old and refers to several not yet resolved issues - I have no idea what the present consensus might be.