[throwaway1777]

They are increasingly common in new developments in the US, but no one is spending money to retrofit old intersections (rightly so I think)

[michaelcampbell]

The ~dozen or so roundabouts near where I live (northern suburb of Atlanta, Georgia) have all been 4-way stop retrofits. And all in the last 10 years or so.

[numtel]

LA and southern California could use some roundabouts. There's so many places with stop lights almost stacked on each other.

[ganjatech]

No one except beautiful Portland, Maine. And probably loads of other towns in New England.

[macintux]

Carmel, Indiana has been retrofitting extensively.