The benefits of having street trees are three fold.
Environmental – Trees filter and reduce air pollutants reduces storm water runoff, therefore reducing strain on city sewer infrastructure.
Aesthetical - enhances the overall appearance of neighborhoods and softens the effect of continuous pavement in the public right of way.
Safety - slows vehicular traffic, while buffering pedestrians from noise, and glare by shading roadways.
BEFORE YOU DIG, always call 1-800-424-5555 to request the location of all underground utilities. Breaking public utility lines is both dangerous and costly! It is a free service. The companies for the water, electric and gas lines will come out and mark your planting strip with different color paints.
Cities have specific requirements for trees planted in the planting strip on the street side of the sidewalk. Always call to get a list of appropriate trees for your area.
I have included the sites for Seattle and Bellingham.
The most popular street trees blooming now are the Thundercloud and Blireiana Plum and the ‘Mt Fuji’ Cherry is out in some places.

Prunus 'Blireiana'
The Blireiana Plum is a hybrid between Prunus cerasifera ‘Atropurpurea’ and Prunus mume, growing between 15 -20’ high with an irregular shape and width of 15’. The flowers are very pretty, delicate, pink to rose color and lightly fragrant and are born on almost bear stems. The leaves open reddish purple, turning deep green bronze by the summer. One of the advantages of this tree is that it rarely bears fruit.

Prunus cerasifera 'Thundercloud'
The Prunus cerasifera ‘Thundercloud,’ a cultivar that has been popular since 1937, is similar to the Blireiana, except that the flowers are smaller and bowl-shaped. It has a more rounded dense shape, growing 25’ x 25’. New leaves open ruby-red turning dark coppery purple for the rest of the season.
These trees will sometimes set a heavy crop of small red fruit, which are edible. They can be messy though if left to rot on the ground.

Prunus serrulata 'Mt Fuji'
Prunus serrulata ‘Mt Fuji’ is a beautiful horizontal spreading cherry tree with semi-double white fragrant flowers reaching 15-20 ft high.
As I want to keep my Blireiana to approximately 10’ high, I usually prune after the flowers have finished.
When pruning always remove dead, damaged or diseased wood first, then remove suckers, usually found growing from the bottom of the tree, then prune for shape and height, making the cut at an outward facing bud.
Jane
Harmonious Garden Artistry
Professional Landscape Consulting|photos