That's kind of what I thought ...

I am guessing it is a green ash as leaves are not very white underneath and branches are sort of rough.

I'm sorry to say, enjoy your ash while you can. Massachusetts is in the Emerald Ash Borer infestation range. Thankfully you are not hit as hard as NYS yet. I sincerely hope they can find a way to stop it.

Here is the MA info on EAB: https://www.mass.gov/guides/emerald-ash-borer-in-massachusetts 

Sadly they are here too.

It already appears to be in the early stages of EAB infestation. 1-2 more years to go.

Pretty positive you have an American White Ash, based on its long leaflet petioles. Check bud scar on end of multi leaflet leaf where unattached from branch. Leaf end of White type will resemble big smile, while Green bud scar is "D" shaped. White Ash is usually one of last species to be killed off by EAB, and Green Ash being one of first succumbing to exponentially building local infestation populations. If you would like to become your most knowledgeable locally regarding EAB and Ash trees checking out my Scottie Ash Seed blog

https://scottieashseed.wordpress.com/

fatamorgana2121, there is no stopping spread of EAB from Canada down to panama. Only delaying inevitable arrival to give local community time to prepare. But we have found a god-sent cure for EAB, which besides fully protecting treated trees two years. Treated trees help substantially lower local borer populations so dramatically that untreated trees within same area survive some 3 or more years longer. Sadly it seems that every new town discovering their first borers must swallow all the outdated misinformation supplied by well intentioned local arborist building experience from past list of facts already learned about DED dutch elm disease over past 45 years. Like...once trees become infected, expensive treatment applications required for remaining life of diseased tree, insecticides have poor success rates, ash is short lived weed tree not worth saving, even treated trees continue to slowly decline and also inevitably need removal. It may all sound familiar, but has absolutely nothing to do with managing ash from EAB. Since DED and EAB have nothing in common. Some local arborist fancying themselves experts, may never learn more than they did when EAB first arrived, after 10+ years later when most trees have died off by then. For myself its like flying back from space after actually personally seeing physical evidence that our planet is indeed round, then facing countless experts who eloquently argue so strongly that Earth is flat. They even get me thinking I might be wrong, and should be committed after holding such a preposterous view. (On a side note, why had no one in past predict what other side of Moon looked like. Most had probably failed to even think Moon had another side. Then when Astronauts orbited around to other side of moon and took pictures, conspiracy theorists then thought it impossible for humans to safely fly through the Van Allen radiation belt)

Only improper application of well proven treatment causes further decline. Products applied against EAB can be even cheaper than fertilizing tree each spring. Even highest cost for Tree-age is not even 1/4th cost of treatment for Elm. If cost of removal $600 or higher, same amount can easily protect tree until selling property or until fatal damaging borer infestation populations inevitably pass locally within 10-12 years. Here in Chicago where first borer discovered in 2006, probably arriving in year 2000 before building up enough population to cause observable damage. As of last year 2017, and especially this year of 2018. Any unprotected trees lucky to survive main event have already been recovering on their own after borer numbers crashed. Since American Ash trees are directly related to super long lived Olive tree family which boasts longest living trees ever planted by humans. Green Ash reaches true maturity from 180-220 and has 300 year lifespan, same as Blue Ash which settlers first dyed jeans blue using bark extract. American White Ash was one of three long lived native species having young trees fashioned by indians into trail marker trees, along with Burr & White Oak. White Ash matures from 350-450, and has 600 year possible lifespan. And why I suggest communities search for their most historically valuable endangered Heritage and Legacy class Ash. White Ash George Washington's father had planted is now 250 old and being protected by national park service. Enjoy!

I'm guessing that choice ash trees are being protected by using systemics, which are really harmfull to the enviroment on their own. I sometimes wonder if the eab will dwindle away once it's destroyed all the ash and fringe trees. I think they found a really old American Chestnut tree growing in Maine that's imune to the blight, but would it be possible there could be an ash somewhere thats imune to the borer? One is a disease, the other an insect, so I really don't know.

Systemics do not help the 1 out of 10 trees in NYS that are ash. It is arboreal genocide. I hope for another answer to be found.

FYI, the article that mentioned the EAB's taste for Chionanthus also mentioned they like olive, as in the ones that produce oil and olives. Systemics cannot be used in such crops. Another solution will be necessary because it is only a matter of time before humans transport the EAB over the Rockies to CA's olive groves.

https://entomologytoday.org/2015/07/22/emerald-ash-borer-infestation-of-white-fringetree-found-to-be-widespread/

https://entomologytoday.org/2017/05/23/olive-tree-is-second-non-ash-species-found-vulnerable-to-emerald-ash-borer/

Experiments are in the works looking for alternatives to systemic insecticides which hopefully will prove to be a self-sustaining control. This is an older article, but friends who own a large parcel in my town have had some of the parasitic wasps released on their property. I am hoping that this experiment proves to be successful. Our area is near a NASCAR racetrack, so I am fairly certain that the EAB arrived in firewood brought in by a few of the bizillions of folks who camp there from out of state.
https://takingactionforwildlife.org/Articles/attack-parasitic-wasps-controlling-emerald-ash-borer-natural-predators

I was glancing at the article, and was wondering if the parasitic wasps they're using are native, or from somewhere else. Wouldn't want another cane toad torpedo to hit US. And I would'nt want these things eating my butterfly cats. There's too few already.

Firewood is a great vector for the spread. It is one of the ways it moved so rapidly here - people dragging firewood to all their favorite parks and campgrounds.

https://www.dec.ny.gov/animals/28722.html

https://www.dec.ny.gov/animals/39379.html