In 2020, bankruptcy courts have been crowded with retailers. So far this year, there were 27 Chapter 11 filings by major chains.

All but seven have something in common besides a pandemic with no end in sight: They depend to some extent, if not entirely, on sales of apparel. Some run too many stores and lack strength in e-commerce, others struggle to get their merchandising right.

While the pandemic, which has clearly sapped demand for apparel, may have tipped some into bankruptcy, the sector's trouble began well before. The long list of bankrupt or nearly bankrupt retailers last year was similarly dominated by those selling apparel and footwear.

"The two words for the apparel business in the last decade are 'change,' as in 'everything changed,' and 'slow,' as in 'oops, we thought nothing changed,'" Lee Peterson, executive vice president of thought leadership and marketing at WD Partners, said by email. "Slow to get online, slow about obvious customer-driven change like BOPIS, slow to close stores when it was obvious no one was going to them, slow to realize Gen Z was all about used clothes, slow on dark stores, slow on slow fashion."

In other words, the business has endured a decade of change that went beyond the age-old vagaries of fashion. Some, if not all, of these five major developments of the last decade will continue to challenge retailers in the next one.

1. The decline of the middle class

Much as the incoming decade will be marked by the pandemic, the dawn of the previous one was defined by the Great Recession.

The economic crisis helped widen an already burgeoning wealth gap. By 2012 just 42.2% of U.S. households earned incomes within 50% of the median, down from just over half in 1970. And for years now it has usually taken two incomes to reach that threshold. Between 2007 and 2017 in the U.S., income growth for those with mean annual household earnings of more than $100,000 rose a staggering 1,305% more than those with less than $50,000, according to a report from Deloitte last year.

Meanwhile, the cost of living is up, with medical costs and student debt in particular skyrocketing, according to that report. That could be why Deloitte this year found that "retailers focused on discount brands and channels have doubled their sales in the last 10 years."

2. The rise of fast fashion and off-price

It's no surprise, then, that cheap fashion knockoffs and name-brand discounts would rule the decade.

By 2010, fast fashion was a force to be reckoned with, as consumers embraced the low-cost, high turnover consumption of "throwaway" clothes. Off-price, which enjoys a similarly robust merchandise pipeline and offers a treasure hunt that holds appeal during good or bad economies, has been on pace to reach $18 billion to $19 billion of incremental sales by 2021, according to a 2017 report on the sector from JPMorgan analysts.

This has come at the expense of department stores, which went from having diverse assortments to selling mostly apparel. In September last year, Moody's piled on another discouraging report for those retailers, with further evidence that their share has jumped to off-price stores. "Although the department stores made significant strides to shorten their supply chains and become more efficient, it remains difficult to compete with the off-price sector on speed and freshness of product," analysts wrote. 

3. Lack of formality at school, work and special occasions

"Casual Friday" was a workplace concession in the 1990s meant to smooth the transition between the workweek and weekend. In the last decade, however, there's been little need for it because most every day is casual. And not just at work. 

"One need only trace the rise of wearing sneakers to one's office, college, opera house, theater, church or temple to see that consumers see no value in 'dressing for work' vs. dressing for leisure," Shawn Grain Carter, professor of fashion business management at the Fashion Institute of Technology, said last year. "Even Goldman Sachs has suspended the Tie and Suit rule once and for all!"

That has upended apparel sales for weddings and other special occassions, and had a particularly devastating impact on menswear. The pandemic has further drained demand for apparel, except for comfort and activewear, like athleisure. That's in part because consumers are still mostly stuck at home, but also because they are worried about their finances.

4. An emerging demand for sustainability

By the end of the decade, fast fashion was under fire as more people began to rethink throwaway consumption and pay attention to the human and ecologogical impact of apparel manufacture.

Last year, McKinsey & Company and Business of Fashion predicted that sustainability was the industry's biggest challenge and biggest opportunity in 2020, writing that "the rise of Extinction Rebellion and the demonstrated ability of Greta Thunberg to mobilise her generation make this ever-more relevant."

The pandemic appears to have fueled that. Nearly half of consumers say the disease outbreak made them more concerned about the environment, according to a report from global management and consulting firm Kearney. In 2019, 71% said they took the environment into consideration when making a purchase at least sometimes, but on March 6 of this year, 78% said they did and by April 10 that rose to 83%, Kearney found.

"This year we see consumers expressing a more direct link between their health and the health of the planet," report co-author Corey Chafin said. "This tells us consumers' pro-environmental sentiments are more than idealistic assertions."

5. The rise of resale

Buying secondhand has morphed, from a way for financially strapped shoppers to find clothes into a choice popular with people of all incomes. The practice remains a way to save money, but is also attracting consumers, especially younger ones, who see it as a sustainable way to reuse, reduce and recycle.

Some retailers have answered the call. Retail Dive 2019 Disruptor of the Year, ThredUp — a resale site that, in contrast to the many clothing retailers filing for bankruptcy, filed recently for an initial public offering — in the past year partnered with a slew of mainstream retailers, including Macy's, J.C. Penney, Madewell, Gap and Walmart. The RealReal — which deals mostly in luxury, recently tied up with Gucci and opened a store on Michigan Avenue in Chicago — went public last year. Urban Outfitters last year launched its own apparel rental company, Nuuly, and Nordstrom is piloting an effort in New York. Rebag focuses on handbags and accessories. There are others, in the U.S. and abroad.

The trend was hot before the pandemic and is retaining heat even now. BMO Capital Markets analysts led by Simeon Siegel said in an Oct. 6 client note that "it is clear that a focus on improving the sustainability of fashion and the expansion of the circular economy is only growing" and they "expect ongoing growth across resale platforms."

As the decade wanes, the pandemic has clarified much of this for apparel retailers, which are now encountering customers with fundamentally changed attitudes about what they wear. 

"The next decade is going to be about 'better,'" Thomai Serdari, a professor of luxury marketing and branding at New York University's Stern School of Business, said by email. "Better garments that last longer, better solutions to reverse climate change, better ways to reach the consumer, better design that is truly innovative and the result of collaborative work, better opportunities for smaller brands to compete in a space where the barriers to entry were too high last decade."