Riley’s 1964 painting “Current,” with its wavy black-and-white lines that seem to move, stood out at “The Responsive Eye,” the 1965 landmark show at MoMA that introduced Op Art to the ...

On a recent Saturday, Alex Garza painted around 120,000 feet of white edge lines on freeway ramps in Lansing and Brighton, Mich., between the hours of 4 p.m. and 4 a.m. “A good day would be ...