Why anti-abortion activists still march on Washington
The Roe v Wade Supreme Court decision in 1973 led to one of the largest anti-abortion marches in the world. Year after year, the March for Life drew tens of thousands of anti-abortion protesters flooding the US capital.
Roe was overturned but March continued, 50 years on.
Abortion debate historian Mary Ziegler, who has written six books on the divisive issue in America, explains why.