U.S. politics is growing ever-more divided, but don't blame Twitter, Facebook and Google for the partisan chasm. Older people are less likely to use social media, but they're posting major signs of increased polarization, based on new research. That's our lead item in this week's economic research roundup, which also takes a look at — and links to — studies about U.S. employment, how disability is distributed geographically, global happiness, and inequality in Germany and America. Political strife: not an internet storySocial media and the internet probably aren't the root cause of political polarization, based on evidence in a new paper by Stanford's Levi Boxell and Matthew Gentzkow and Brown's Jesse Shapiro.First of all, it's worth noting that the divide is real. In 1960, only 5 percent of Republicans and Democrats would have been displeased if their son our daughter married outside of their party, but in 2010 that rose to half of Republicans and almost a third of Democrats. The worst of the strife is coming from senior citizens: Americans older than 75 have shown a bigger increase in polarization than their younger counterparts, based on their responses to the American National Election Study. That's relevant because they're much less likely to go online to communicate, with less than one in every five people older than 75 using social media in 2012 versus 80 percent of the 18-39 group.The finding "s;rules out what seem like the most straightforward accounts linking the growth in polarization to the internet,'' though "s;young adults polarized through social media might in turn affect the views of older adults or might indirectly influence older adults through channels like the selection of politicians or the endogenous positioning of traditional media."s; No cigar on full employmentThe labor market isn't as tight as it appears, based on new research from the San Francisco Fed. After adjusting for demographic changes, the U.S. jobless rate is 0.3 to 0.4 percentage point higher than it has been in past labor market peaks. Once researchers Regis Barnichon and Geert Mesters adjust to account for shifts in the labor force composition, they find that the unemployment rate stands at 5.2 percent as of February, not the 4.7 percent the Bureau of Labor Statistics reports. "s;In fact, our adjusted rate is higher than all its previous lows since 1976,'' they write.Three factors have driven the decline in the official number: the baby boom generation's aging, the fact that young workers are getting into the labor force later, and the fact that women are sticking around in the labor force, meaning that they are skipping the spells of unemployment associated with exiting and re-entering the job market.The geography of disabilityDisability insurance use is becoming concentrated in the places with the worst economic prospects, based on new St. Louis Fed research. Disability enrollment tends to increase when unemployment rates rises, and that relationship held in the last recession. From 2009 to 2015, however, unemployment dropped and disability insurance payments continued to climb. That surprise increase wasn't evenly spread across the country: disability payouts became more concentrated in the small share of counties with still-high unemployment in 2015. The takeaway is that disability's "s;rise is not a result of increased hardship on average. Instead, the counties that are doing poorly along one economic indicator — unemployment — now fare even worse along another,'' David Wiczer writes.