Designers are rolling out their spring lines and the runways are looking more diverse than ever. But the comparative abundance of models who are people of color didn't happen overnight.There was the occasional — very occasional — model who wasn't white in the 50s and early 60s on runways. But African-American models put American couture on the map in 1973 when they walked the runway in France in what's become known as The Battle of Versailles.Almost instantly, black models were The Thing for a brief, halcyon period. But by the mid-80s, with a few glorious exceptions, the catwalks had regained a distinctly milky aspect.Many designers' casting directors — the people choose models for shows — would specify they wanted a "certain look." And for a long time that look was very, very pale.Things got so monochromatic that in 2013 Bethann Hardison, a former model and modeling agency owner, and supermodels Iman and Naomi Campbell formed an organization called Diversity Coalition, to insist on runways that included women of color. The Coalition even penned a manifesto addressed to the international fashion industry, saying the runways needed to be a lot more varied in hue, especially at the darker end of the spectrum."The decision to use basically all-white models reveals a trait that is unbecoming to modern society," the authors wrote.Then they named names.That, said James Scully, is what gets people's attention. Scully, a model, casting director and activist, recently wrote an Instagram post that claimed that the House of Lanvin had requested no women of color be included in the go-sees for casting its latest show.Lanvin insisted that was incorrect—but in the end, 6 women of color were in its lineup.Earlier this month, The Fashion Spot, an online forum for fashion insiders, released its Runway Diversity Report for Fall 2017. The report surveyed 241 shows during the fall 2017 season. Almost 28 percent of the models in those shows, collectively, were people of color. The report looked at national and international runways and found the highest racial diversity across the four major participating cities (New York, London, Milan, and Paris) was in New York, where 31.5 percent of the models were people of color.Jennifer Davidson, editor in chief of The Fashion Spot, told The New York Times "I personally don't think 31.5 is enough, but it's definitely an improvement."It's a tricky thing, casting. Directors have a vision for their lines — but what if that vision doesn't include a more inclusive palette? "It's an aesthetic decision, it's not personal" used to be a standard response from some designers. Marc Jacobs is one of the designers the Diversity Coalition called out in 2013 for being diversity-impoverished. He again found himself in the fashion world's crosshairs last year when he sent mostly white models down the runway in rainbow-colored yarn dreadlocks.Jacobs was mystified at some of the outrage from people who charged him with cultural appropriation. Openly questioning why white models wearing dreadlocks was offensive, he suggested that his critics wouldn't "criticize women of color for straightening their hair." Eventually Jacobs apologized on Instagram "for the lack of sensitivity unintentionally expressed by my brevity."And, tellingly, he was among the designers with one of the most diverse runway lineups for fall 2017 — 66 percent models of color (see photo above).The Fashion Spot has begun to tabulate not just racial diversity, but other kinds as well: designers that use older models, models who are transgender and plus-sized models. Of those groups, there has been more representation of plus-sized women than any other difference, but the door has been opened for other kinds of diversity. (Dolce & Gabbana dressed Italian nonnas (gramdmas) in its current campaign, and have for a few seasons. At J Crew, entire families replaced models to show off the retailer's wares.)These steps are not only good, but smart: the world, and fashion's consumer base, is getting more varied by the day. Having the runway mirror the real world a little more closely will lead to the industry's favorite sound: ka-ching, ka-ching. Copyright 2017 NPR. To see more, visit http://www.npr.org/.