Looks like a Manitoba Maple. Did you plant it?

Regardless of what kind of tree, this is a kind of weed tree down here in Toronto. Gets established everywhere.

Here is a link that might be useful: weed trees of Ontario

Acer negundo, a weed tree that is appreciated in the west and a few other countries. Here in Ontario it is a nuisance if allowed to grow and flower producing seeds that germinate too easily. Please don't allow it to do that!!
I speak of it distastefully because on our country property there were a few planted by the farmers who lived here before 1974. Now we have so many Manitoba Maples all around us and have spread up and down the concession road. The seeds land in car windows spaces, trailers, truck beds. Innocently we have been giving them a free ride to new territory!! Yuk.

Manitoba maple. It is considered a âÂÂjunk treeâ in GTA and last year I noticed, in the York Regional Forest, these trees were deliberately sprayed by herbicide in order to kill them and stop them from spreading in the forest. Kill it while you still can and plant something more useful and beautiful in its place.

Correction: trees. Here's another view.

Manitoba Maple in Manitoba, Saskatchewan, and Alberta...fantastic.

Manitoba Maple in southern Ontario...invasive, very fast growing, weak wooded, rot prone, short lived, and ugly (especially when covered in brown maple seeds). Somewhat dangerous too...neighbour had a big one fall last night at 1AM. The crack-crack-crack had the entire neighbourhood thinking someone set off more late night fireworks.

Well, yes, they certainly do grow out here - like weeds - seeds sprouting EVERYWHERE and if you don`t pull them or mow them down right away they really take hold. There are new varieties out that are seedless(Sensation)but unfortunately I`m not surrounded by those!!!!! There are so many other, lovelier trees out there I would not sacrifice the space for a Manitoba Maple.