Artist Steve Powers is returning to his hometown with an ambitious new project, “Love Letter.” The series of murals covering 50 walls and rooftops will be form letter of love visible for 20 blocks on the Market-Frankford elevated train line. The message will not only come from the neighborhood but be painted by residents as well. With project collaborators at the Philadelphia Mural Arts Program, Powers is opening a sign making school to teach and employ young adults on the project’s construction beginning in August.