why is William Penn is important in US history?

why is William Penn is important in US history?
please provide detail or a essay

In addition to being religiously tolerant and treating the indigenous peoples fairly, William Penn was also one of the earliest city planners.

He laid out his “Grene Country Towne” of Philadelphia in a grid pattern of numbered streets running north and south and named streets (most after trees, in keeping with Quaker simplicity which shunned honoring people in this way) running east and west. He also provided for plots of land which were intended to be left undeveloped as well–they survive now in the little squares known as Franklin, Washington, and Rittenhouse, as well as Logan Circle, all found in Center City Philadelphia.

Penn often referred to his colony as a “Holy Experiment,” for he felt that there was no reason for one person or group to make life miserable for others because of differences in religious opinions, and if more colonists had followed his example with regard to Native Americans, a great deal of bloodshed on both sides could have been avoided–indeed, the infamous “Walking Purchase,” which effectively stole a pretty big chunk of real estate, would never have been condoned by him if he had still been alive.

Ah, well. Great people often, alas, have offspring who don’t necessarily follow the paths of their forbears.