She committed suicide by hanging, said police officials, who confirmed to The Washington Post that a note was found at the scene.
Spade began her career at Mademoiselle magazine, where she worked her way up from an entry-level to senior editor for accessories. Often disappointed at the selection and prices of handbags available for fashion photo sessions, she decided to start a business and design them herself.
The designer bags from Prada and Louis Vuitton were too precious, in every way, to suit Spade, who preferred a simple woven bag with not zippers or flaps.
"I said to myself, 'Where's a bag that I can afford, that's simple, that's not saying too much and that I won't be embarrassed to pull out every season?' " she told the Toronto Star in 1997.
With no training in design, she went to work in her apartment, using construction paper and Scotch tape to find the right dimensions. Her first handbag was made of burlap, the cheapest material she could find.
"I sat down with some tracing paper, and I knew immediately what the shape should be - a very simple square," she told Fortune Small Business in 2003. "At the time no one was doing anything that clean. The shape gave me a real flexible canvas for applying all the ideas I had for a lot of colors, patterns, and fabrics."
She took her designs took to a manufacturer in Brooklyn and showed her first six models at an accessories show in 1993. She sold a few, but not enough to cover the cost of the booth at the exhibition hall.
Then unmarried and still known by her maiden name, Kate Brosnahan, she searched for the right brand name, trying out several before taking the advice of her boyfriend, Andy Spade.
"Andy kept saying the whole time, 'Kate Spade, Kate Spade - listen to how it sounds,' " Ms. Spade told the New York Times in 1999. The Kate Spade company was formed one year before she and Andy Spade were married in 1994.
She had another stroke of inspiration the night before another accessories trade show in New York.
"There was something missing," Ms. Spade told the Boston Globe in 1999. "We needed something for the eye to go to."
She decided removing the small black labels written in lowercase lettering - "kate spade new york" - from inside the handbags and put them on the outside. She stayed up all night, hand-stitching them to the exterior or her bags, giving them just the visual texture they needed.
Whether made of leather, nylon, canvas, tweed or other materials, a Kate Spade bag a distinctive look, with almost an architectural solidity. It was easy to carry and didn't overwhelm the rest of a woman's ensemble. Her bags often came in bright hues or pastels, with vibrantly contrasting linings and simple handles.
"I don't like really long straps," Spade told Newsday in 1996. "You might as well have your bag on a leash and drag it behind you."
Her handbags were picked up by Barneys and other department stores, and Spade began recognized as one of the fashion world's top designers of accessories. Vogue and other magazines featured her creations, and celebrities such as Gwyneth Paltrow were spotted carrying Kate Spade bags.
Her husband, who is the older brother of actor and comedian David Spade, left his job in advertising to become chief executive of the Kate Spade corporation. By the late 1990s, Ms. Spade's simple but chic handbags had become especially popular with upscale, working women.
In 1998, she and her husband sold 56 percent of their company to Neiman Marcus for $33 million but retained creative control over the products.
"They are the most unlikely people that you expect to find in the fashion world," Leonard Lauder, chairman of Estee Lauder, told Vanity Fair in 2002. "Kate is the girl next door. I've been acquainted with so many fashionistas over the years, and she is the anti-fashionista."
Spade's personal design aesthetic owed little to the passing whims of the fashion world.
"People would come in and want aubergine because it was the color of the season," she said in 2003. "They would say, 'Everyone's doing it!' And I'd say, 'Well, you're probably covered then.' "
In time, Spade expanded her design offerings to paper products, sunglasses, shoes, luggage and clothing. She even designed flight attendants' outfits. In 2002, she appeared on an episode of "Just Shoot Me," a sitcom starring her brother-in-law, and branched out into writing books and general lifestyle advice. Kate Spade specialty stores opened around the world.
Critics said the quality of her materials declined, and the value of genuine Kate Spade items was undercut by a flourishing market of counterfeit bags. By 2007, the Spades had sold their remaining interest in the company to Neiman Marcus for $124 million. The Kate Spade line was sold in turn to Liz Claiborne and is currently owned by a corporate entity called Tapestry.
Katherine Noel Brosnahan was born Dec. 24, 1962, in Kansas City, Missouri. Her father owned a construction company, and her mother was a homemaker.
She followed few fashion trends, other than shopping for bright-colored items at thrift stores, to stand out from her sisters.
While attending Arizona State University, she worked in a department store, where she met Andy Spade, a fellow student. She graduated in 1985 and later settled in New York, reportedly with only $7 to her name.
Through an employment agency, she found an entry-level job at Mademoiselle, where she spent eight years. When she launched her design company, she had an agreement that she could return to the magazine if the venture failed.
In recent years, Ms. Spade launched a new accessories line, Frances Valentine, named in part after her daughter, featuring new lines of handbags, shoes and other items.
Survivors include her husband and their 13-year-old daughter.
Known for her whimsical, slightly old-fashioned sense of style, Spade offered this fashion advice in a 2006 interview with the Kansas City Star: "Dress for yourself. It's so much more fun."
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)