When was the last time the yellowstone caldera erupted?

The last giant caldera-forming eruption was about 640,000 years ago. However, if you look at the West Thumb section of Yellowstone Lake, this is a remnant of smaller caldera that formed about 120,000 years ago. The most recent lava eruption of any kind was a rhyolite flow eruption (Pitchstone Plateau) about 70,000 years ago.