2016-4-24 unknown flowering tree Newark, DE

It can't be Pin Cherry because that has leaves even longer than P. serotina.
http://www.discoverlife.org/mp/20q?search=Prunus+pensylvanica

Pin Cherry (Prunus pensylvanica)
native
Pin cherry, Fire cherry, Wild red cherry, Bird cherry, Pigeon cherry
http://www.wildflower.org/plants/result.php?id_plant=PRPE2
slender, sometimes shrubby, tree, 35-50 ft. tall

bright red branches
reddish to yellow-orange, mature bark
flat-topped clusters of white flowers
bright red fruit
small tree or shrub with horizontal branches
narrow, rounded, open crown
shiny red twigs
tiny red cherries
Fall foliage is colorful

great pic of leaves and tiny cherries:
http://tenn.bio.utk.edu/vascular/database/vascular-photos-enlarge.asp?CategoryID=Dicots&FamilyID=Rosaceae&GenusID=Prunus&SpeciesID=pensylvanica&Phot