To what sports event does "The Run for the Roses" refer to?

The Kentucky Derby is, without a doubt, America’s most iconic horse racing event. England has Royal Ascot, and Australians flock to the Melbourne Cup, but few meetings capture the spirit of a nation quite like the “Run for the Roses.” So named for the garland of roses that is draped over the winner, the Kentucky Derby traces its rich history back to 1875 when Colonel Meriwether Lewis Clark Junior decided to inaugurate a race in his home state of Kentucky. Clark—grandson of William Clark of the historic 19th century Lewis and Clark transcontinental expedition—had been influenced by a visit to England’s Epsom Derby. Indeed, the Kentucky Derby was originally run over a distance of 1.5 miles—the same distance as the Epsom event—before being shortened to its present 1.25 miles in 1896.

Source: CNN