Why are women lawmakers wearing white at the State of the Union?

Even in the early 20th century, women seeking the right to vote knew how to get the media's attention.

In demonstrations and parades, the suffragists donned white dresses meant to generate photo coverage in the daily newspapers. The color choice also echoed England's suffrage movement, which used purple, white and green as its official colors.

The white outfits dozens of female lawmakers wore to the State of the Union address Tuesday night were a visual tribute to the U.S. suffragist...