Mitt Romney won both states that held primaries on Tuesday. But his margin in his home state of Michigan appears narrow enough to keep the GOP nominating contest lively for some time to come.

NPR projected wins for the former Massachusetts governor in both Arizona, where he won comfortably, and in Michigan, where he led Rick Santorum, 41 to 38 percent, with 99 percent of precincts counted.

Something that only comes around once every four years and doesn't involve either politics or Olympic competition deserves its own mention:

Wednesday is Feb. 29.

Leap day, that is.

Our friend Linton Weeks has put together a handy list of 24 things you could do with the extra 24 hours. (And yes, we know that some of you have already started your day; but, hey, we're an East Coast-based blog.)

Americans who turn up in the emergency room to get dental care aren't lost, they're probably just running out of options.

According to a new report from the Pew Center on the States, more than 800,000 visits to the ER in 2009 were for toothaches and other avoidable dental ailments.

Found time! An extra day. How will you use it? Here are 24 ideas. None of them takes longer than an hour. Because time is tight, time is of the essence, time is money. And if you don't have time to get to everything on the list, don't worry. Maybe in 2016.

Feb. 29, 2012 Hour By Hour:

Virtually everyone expected Tuesday's big political news to come blowing out of Michigan, the big industrial state, where Mitt Romney and Rick Santorum were vying to win that state's GOP presidential primary.

But little Maine managed a national political bombshell of its own with the surprising news that Sen. Olympia Snowe, the 65-year old, three-term moderate Republican senator, won't seek re-election.

From a statement she issued, it appears Washington's partisan bickering just got kind of old for the senator.

Some of the first people in the Bay Area were Native Americans – members of the Ohlone tribe, who settled around what is now the city of Richmond. Beginning in the 1920s, another group of Native people found their way to the Bay Area. They were migrants from the Acoma and Laguna tribes of the Southwest. When they arrived, they took up an unusual living arrangement: in boxcars, parked on the dead ends of the city’s railroad tracks.

Another Tuesday, another critical day for the 2012 Republican presidential contenders.

This time the locations are Michigan, where most polls close at 8 p.m. ET, and Arizona, where voting ends at 9 p.m. ET. The story political junkies are watching closest: Will former Massachusetts Gov. Mitt Romney, a Michigan native, hold off a strong challenge there from former Pennsylvania Sen. Rick Santorum?

Also on the ballots, of course: former House Speaker Newt Gingrich and Rep. Ron Paul, R-Texas.

In the mid-1800s, the Gold Rush brought enthusiastic settlers westward, from across the United States. At the same time, another migration was flowing eastward.

Over three decades, the country’s Chinese population grew from 4,000 to over 100,000. The immigrants who landed on California’s shores followed the Transcontinental Railroad across the state, building pockets of community along the way.

When he returned from Afghanistan and saw his partner waiting to welcome him home, "four years of pent-up emotion and secret love" just seemed to naturally lead to "what felt like an eternity kiss," Marine Sgt. Brandon Morgan told NPR this afternoon.

On February 29, 1932, the BBC launched its Empire Service on shortwave – 80 years later, you know it as the World Service, and hear it throughout the day on KALW.