In June last year the State of Massachusetts was the first to market in the USA with a green Muni. They're about to go again - their bond sales calendar has them going to market next week, on 17 September, with a new $250 million "general obligation" green bond.
The Massachusetts Treasury have been doing a lot of work on showing investors exactly where bond proceeds are going, in minute detail. Keep an eye out for disclosures with this next bond.