With high power validation from an international colleague - London Mayor Sadiq Khan - some three-dozen American mayors immersed themselves in four days of discussion and experience at SXSW the annual technology, policy and arts festival in Austin, TX.

The mayors' wide ranging conversations about common issues - from immigration and workforce to the fight against opioid addictions and for equity - took place in a host city that has been buffeted by a fight over the future of public transportation.

Last year, Uber and Lyft were conspicuous in their absence at SXSW. The city was at odds with the transportation network or ride-hailing companies - and ultimately preempted by the state legislature. The big players are back this year with new entrants in a more expansive category of mobility service providers who are placing bets on cities themselves to connect the first and last mile of urban transportation.

Our roundtable also choose the key takeaways from the civic side of the conference with the mayors.