It looks like some type of sumac. Hard to see the top.
Check Google images.
It can be poisonous.

LOL. That's a "tree of heaven", Ailanthus altissima, probably the #1 weed tree in North America. AKA, the ghetto palm. Be glad your yard is free of it.

Castiliana, this is not a plant that you want to bring into your property.

What an interesting plant, though I have never noticed any foul odor to the blooms. I am curious how invasive it is in my area, with the 15+ year drought we have been averaging about 6 inches of rain a year add temps over 100 in the summer most spreaders bake to death. I do live fairly close to a golf course though so perhaps you are right it would be a poor choice as I imagine it would grow quite readily there.

we never water it but there are always new babies popping up everywhere.

I think you answered your own question as to invasiveness.

Originally brought into the American West by Chinese workers in the 1800s. Said to be the most common street tree in Bisbee AZ.

Here in NW Oregon, roots from trees 50 feet distant go under foundation footings and into crawl spaces. In AZ, they would just go straight down to find water.

I have been trying to figure out the last day what to do about it. the tree itself doesn't bother us, it is not stinky and it is the only tree/shade on the property as trees just do not grow at random here. It does not seem to be on the az controlled invasive species list, but it is in one of our extension office pamphlets as an invasive so now I am not sure if i am required by law to kill it or if it is fine where it is. To be honest now that I know what it is i see several around our historic district and ours are probably 20 years old or older. We have no water ways, streams or creeks or rivers here and our water table is 300-1000 feet down so i am thinking short of the occasional house with sprinklers (most landscaping is rock and gravel) or the golf course even tree of heaven doesn't have too many places it can spread to. I would like to keep them if i can (added bonus we are a book store and it is the "a tree grows in Brooklyn" tree) Does anyone know what is required? if it can stay or must go?

Can you get a closeup of the foliage? As someone who lives in Philadelphia, I am quite familiar with Ailanthus, and I don't believe that is this.

To me it does and it doesn't based on other photos. the leaves seem longer but it does have the heart shaped scars on the trunk and the seeds look right. Here is one i took of a growing tip on one of the mature trees

Flowers

Definitely Ailanthus.

Crush a few mature leaves and notice the musty, acrid, peanut-butter odor.

There are female and male trees. The females shower down twisted drill-bit seeds that sprout readily, and the males shower down a coarse powder, preferable to the seeds, but the odor is present during male bloom.

They are a handsome tree in summer and produce fairly dense shade. Any winter ice load will break smaller brittle branches.

How big do these get in your town?

I am not fully sure how old these are but the two oldest are about 6-10 inches in diameter in the trunk and are tall enough to reach over the roof our our warehouse so perhaps 15 feet at this point. Dainty compared to the usual mullberries and cypress used in landscaping around here but they may be younger. We have only been in the building a year and a half and they have not changed much in that time. The others in the back are quite supple and arch over once they reach about 8-10 feet it seems.

If saltcedar says Ailanthus, I'll agree that it is!

AAAAAAAAAAAAaaaak the dreaded basal lobes on the leaves! RUN!!!RUN!!!!

Here is a link that might be useful: ailanthus fact sheet