Republican voters in Wisconsin, Maryland, and the District of Columbia go to the polls this morning in another round of presidential primaries. Rick Santorum is trying to stop the momentum of Mitt Romney, but is facing an uphill battle after Romney received the endorsement of several of the state's top Republicans. In other headlines: seven were killed in a deadly shooting spree at a Christian university in Oakland, California; the Supreme Court rules officials can strip search after an arrest no matter the crime; and Syrian officials have agreed to comply with a UN brokered peace plan by next Tuesday.

Sanford, Florida, where 17-year-old Trayvon Martin was shot and killed by 27-year-old George Zimmerman over one month ago, is currently host to the worst kind of attention a small town could possibly imagine. After weeks of protests around the country, the question lingers as to whether the small town's image will be eternally marred the way that Selma or Birmingham, Alabama still evoke the civil rights movement of the 1960s. What connection does this town have to the long history of the American civil rights movement? For answers, we turn to Isabel Wilkerson, a Pulitzer Prize winning journalist and author of "The Warmth of Other Suns: the Epic Story of America’s Great Migration."

Instead of just measuring economic health, should we be measuring our levels of happiness? That’s a question the United Nations is taking up this week in a session called "Wellbeing and Happiness: Defining a New Economic Paradigm." But how worthwhile is the "pursuit of happiness" in the first place? Wake Forest English professor Eric G. Wilson is the author of "Against Happiness: In Defense of Melancholy." He argues that Americans' fixation on happiness comes at a cost.

On Monday, the Supreme Court ruled 5-4 that authorities may strip-search people arrested for any offense — no matter how minor — before they are admitted to jail. In Florence v. County of Burlington, Albert Florence argued that he was subjected to humiliating strip searches after he was mistakenly arrested in 2005. However, according to the court's majority opinion written by Justice Anthony Kennedy, the need to protect the safety of prison inmates justifies the use of "thorough searches at intake for disease, gang affiliation, and contraband" by correctional officials. Anita Allen, professor of law and philosophy at University of Pennsylvania explains how the court reached its decision.

All presidential campaigns have to report expenditures of $200 or more, and they'll all throw in some token small stuff, but no one takes campaign finance disclosures more seriously than the campaign of Texas Congressman Ron Paul. Every bank fee, refueling, and purchase of morning coffee is reported in the Paul campaign's FEC reports. How do the other major candidates compare to the Paul campaign? Kim Barker, reporter for ProPublica, explains what a campaign's transparency tells us about the candidate.

Have you ever looked at a stop light, a slice of pizza, or the hot air coming out of your hair dryer, and wondered: What and who went into making this? A new four-part PBS series called “America Revealed” delves into this question; scaling back from small everyday items to give viewers a big picture view of how America functions. Along the way, it doesn’t just unveil the secrets of how stuff is made; it also tells a story of America’s history and people. The series is hosted by Yul Kwon, an attorney, businessman, and technology expert, who you might also recognize as the 2006 winner of the reality show “Survivor.”

Police in northern California have no motive for a deadly shooting spree Monday on the campus of a small Christian university, where seven people were killed and at least three more wounded. In other headlines, voters in two states and the District of Columbia cast their ballots today for the presidential primary; the United States is offering $10 million for the capture of Pakistani militant leader Hafiz Saeed; more than 3,100 illegal immigrants have been arrested in the country's largest-ever operation to crack down on illegal immigration; and the Kentucky Wildcasts are NCAA Division I champions after a 67-59 win.

Tonight's primary results may ultimately decide the fate of the GOP nomination contest. If Mitt Romney wins Wisconsin, he may effectively seal the deal and his inevitability will likely go unquestioned. But if Rick Santorum can pull out a victory in the Badger State, all eyes will be on the nominating contest in the former Senator's home state of Pennsylvania three weeks later. We're joined by Takeaway Washington correspondent Todd Zwillich and Republican Strategist and Takeaway Contributor Ron Christie.

ABC and NBC are staging a rematch this morning of the memorable contest between Katie Couric and Sarah Palin in 2008. Couric's interview with Palin in 2008 stalled the meteoric momentum for the vice presidential candidate and fueled the comedy writers at Saturday Night live for months. Now the two battle for top ratings between the Today Show and Good Morning America. Bill Carter is a media correspondent for our partner The New York Times and author of "The War for Late Night".

Syria says that it will start to implement Kofi Annan's six-point peace plan. But skeptics fear that Syria's government will not fully comply with the plan or with its April 10 deadline. The plan calls for a UN-supervised ceasefire by all parties, withdrawal of soldiers and heavy weapons from cities, and delivery of humanitarian aid. Barbara Plett, UN correspondent for our partner the BBC, joins us with her exclusive reporting from the region.

When she was only 15 years old, a girl in Washington state ran away from home. Within 36 hours, she was lured into the sex trade. And for over 100 days she was trafficked, with sites like backpage.com advertising her as an 18-year-old escort. Two years later, that girl is 17, and back at home. Her mother is working tirelessly, trying to prevent other children from living the same story as her daughter. Andrea Powell is the executive director of FAIR Girls, which seeks to prevent the exploitation of girls through empowerment and education. FAIR stands for free, aware, inspired and restored.

Republican primaries take place today in Wisconsin, Maryland and the District of Columbia. We're checking in with voters today, including Mitt Romney supporter Deborah Edattel in D.C., conservative blogger David Blaska in Wisconsin, Peg Edquist from Wisconsin, and Santorum supporter Julaine Appling from Wisconsin.