The story behind the Obama Administration's most enduring—and most contested—legacy: reforming American healthcare.

Our first spring in the White House arrived early. As the weather warmed, the South Lawn became almost like a private park to explore. There were acres of lush grass ringed by massive, shady oaks and elms and a tiny pond tucked behind the hedges, with the handprints of Presidential children and grandchildren pressed into the paved pathway that led to it. There were nooks and crannies for games of tag and hide-and-go-seek, and there was even a bit of wildlife—not just squirrels and rabbits but a red-tailed hawk and a slender, long-legged fox that occasionally got bold enough to wander down the colonnade.