Why did Nancy Pelosi use so many pens to sign Trump impeachment articles?

House Speaker Nancy Pelosi used several pens to sign the impeachment articles against US President Donald Trump on Wednesday. Since Franklin Roosevelt, US Presidents have frequently used multiple pens to sign high-profile pieces of legislation, so they can be offered as souvenirs and historical keepsakes. Pelosi picked up each pen, signed a bit, and handed each one to a lawmaker.