In 1999 Williams headed over the border into the United States to compete in the NATC Women's Trials Championship . She won the 1999 series ahead of American rider Pam DeBruin then returned to defend her title in 2000 and 2001, both years winning ahead of her sister Kerry Williams. They repeated their one-two combination again in 2003 and 2004, then Christy won in 2005 ahead of Louise Forsley. Williams returned to take three more titles in 2008 until 2010.