On Sunday, Amy Cragg finished third at the Tokyo Marathon with a time of 2:21:42, slashing more than five minutes off her personal best. But given Cragg’s credentials on the roads, the time served more as an affirmation than a breakthrough. 

Her previous personal best came from her first marathon — a 2:27:03 in Los Angeles in 2011 — a time she equalled three years later at the Chicago Marathon. Since then, she has won the Olympic Trials and taken a bronze at the world championships, so while she was a 2:27 marathoner, that was almost as misleading as calling Meb a 2:08 marathoner. Sometimes accomplishments outpace the number affixed to an athlete.

But Cragg's new personal best does help quantify how strong the American women will be in the marathon this year. Her time in Tokyo put her fifth on the U.S. all-time list. Two of the four women in front of her — Shalane Flanagan and Jordan Hasay — are actively competing. 

Since 2008, no more than two American women have put up a top 60 mark on the yearly list. Cragg’s run in Tokyo guarantees that they will have at least one before the spring marathon season even begins. 

However, times aren’t always to best metric to demonstrate marathon success. The variability of courses and conditions makes it tough to compare performances. Cragg is a perfect example. When it comes to race selection, she’s zigged where others have zagged. She’s only raced New York once and has never run in Boston. She ran the world championships last summer when other top Americans passed on the race. 

All total, Cragg has run against Shalane Flanagan and Desiree Linden only three times in her career, the 2012 Olympic Trials, the 2016 Olympic Trials and the 2016 Olympics. She’s never raced against Huddle or Hasay in a marathon, though those two are new to the distance. 

So perhaps a better metric to assess American strength is performance is in World Marathon Majors. There, the numbers bear out that last year American women had their best year in the marathon since the World Marathon Majors series was created in 2006.  

**Tokyo became a World Marathon Major in 2013. In 2010, 2014, and 2018 there is one less opportunity to run a World Marathon Major because there are no World Championships or Olympics**

With Shalane Flanagan, Molly Huddle, Jordan Hasay, and Desiree Linden all set to race in Boston, the numbers for 2018 will surely increase in April. If most of that group races again in the fall, they could top last year's output. What is the cause of the upswing? Shalane Flanagan’s victory in New York City was an clear signal that American women could win major marathons even in this deeply competitive era, but this rise in performance isn’t confined to one person. 

The U.S. seems to be getting the benefit of having runners of overlapping eras capable of performing at a high level. The next crop of American women — led by 26-year-old Hasay — is already competing with the best in the world. At the same time, marathon veterans Flanagan (36 years old), Cragg (34), and Linden (34) haven’t seemed to slow down. In many cases they are running better than they ever have in their career. 

This phenomenon isn’t confined to the United States. Three of the best women in the world — Tirunesh Dibaba, Mary Keitany, and Edna Kiplagat — are 32, 34, and 38, respectively. None is showing any sign of slowing.  

Boston could be Flanagan's last race. She has spoke openly about retirement before her victory in New York City. But even if she retires after Boston, it won't be enough to slow the ascendence of the American women. All the pieces are in places for a historic year.