Thousands of people are running across the US in a charity relay organised by British runners.
Danny Bent, Kate Treleaven and Jamie Hay, all from Devon, set up One Run for Boston for the victims and families of the Boston marathon bombings.
Three people were killed and more than 250 injured last year when two bombs exploded at the race on 15 April.
The 3,500-mile (5,600km) relay from Los Angeles to Boston is due to finish on 13 April.
It is the second time the event has been staged.
'Spirit of positivity'
More than 2,000 runners took part last year, raising about $91,000 (£54,000) and the organisers are hoping to reach $1m (£600,000) this year.
"This second event was inspired by runners in the States, who we have kept in touch with following the 2013 One Run for Boston," Mr Bent said.
"Many of them told us it changed their lives, fostering such an amazing spirit of positivity that it helped them recover from the Boston bombings and, in many cases, other personal tragedies.
"We have been overwhelmed by the support already received for 2014, and we hope it will continue to transform lives in Boston and beyond."
The lily-inspired torch that will be carried across 14 US states has again been designed by Plymouth University graduate Jon Parlby.
"The new design is made from several component parts and at night, the baton lights up with a green stem and white head," he said.
"It is bright enough to light the road for the runners."
Starting from Santa Monica Beach in Los Angeles at 20:00 GMT, runners will travel through California, Arizona, New Mexico, Texas, Oklahoma, Missouri, Illinois, Indiana, Ohio, Pennsylvania, New Jersey, New York, Connecticut and Massachusetts.
The stages, although varying slightly in distance, average about 10 miles (16km).
The man accused of the bombings is due to stand trial in November.
Dzokhar Tsarnaev has pleaded not guilty to 30 charges - 17 of which carry a possible capital punishment sentence.
Prosecutors allege that the 20-year-old set off two pressure cooker bombs with his older brother Tamerlan, who later died in a police shoot-out.
- 6 June 2013