Amelanchier species are blooming now in PA and have the irregular shape you speak of. Common names are serviceberry, shadblow, shadberry. It is a native tree to Pennsylvania that looks beautiful along the Deleware River. The nicknames come because they bloom at the same time as the shad are running in the spring.

It could be a shadblow, but isn't it more likely to be some sort of cherry?

I haven't seen many amelanchier planting in parking lots, maybe because they can be delicate and picky about moisture conditions. And the shadblow in my front yard isn't quite blooming yet, needs another week to really pop.

They're beautiful trees. Birds love their berries, too.

Too early for Amelanchier...sounds like prunus..maybe 'Hally Jolivette' which has wihte flowers. Wide spreading, can be shrubby.

Some sort of plum?

They could be Pyrus calleryana 'Autumn Blaze' which is noted for it's non pyramidal habit.

Here is a link that might be useful: other pears still being planted other than 'Bradford'

No, it has a sturdier trunk than that Pear tree. Perhaps a kind of cherry. If I can remember my camera, I'll take a picture. Thanks for all the guesses!

I was thinking this could be a flowering pear. They have a pretty tidy appearance.

Without a picture, or description of bark or leaves, it's hard to tell, but your likely suspects are some type of cherry or crab apple. Sargent crab is a low growing, spreading kind of crab that I know is popular in commercial landscaping. Looks nice in spring and then has bright red berries in late fall, early winter. I see it commonly around professional buildings and in some parking islands.

Amelanchier is popular too, but NOT for parking islands. But amelanchier, flowering pear, cherries and crabs all bloom in somewhat similar times so what you're seeing could be more than one type of tree. This year the bloom cycle of everything seems to be mixed up. Around here it stayed cold for so long that the spring show was rather subdued, and it didn't have it's usual succession. Bloom times were very short.

If it's in the Philly region in the second week of April, it won't be a crabapple!

MAny of the larger cities in the eastern US had a streak in the 60s and 70s of planting common pear and Asian pears as resilient median trees in parking lots at malls, stadiums, etc.

Common pear has a muscular trunk and an irregular bud rounded overall canopy, Pyrus communis. It readily fruits and birds spread the seeds all over, including in roadsides so at first you might think (when in bloom in spring) that it is the native wild plum (Prunus americana). Asian pear is Pyrus pyrifolia.

Pin Cherry is usually the first white blossomed tree you'll see in the spring. Prunus pennsylvanica) Grows wild in the woods, along the rivers and roadway.
Pam

Thanks. Now they look like every other green leafed tree, so I don't know if a oicture would help.

Hey -- my name is Pam, too.

Pam, a closeup of the foliage, twig and bark could probably get you an ID! The best place to post that stuff, along with when it bloomed, would be on GardenWeb's "name that plant" forum. Their are some very, very knowledgeable folks there.