(AP) — Missourians who live in rural areas are far less likely to have health insurance than those living near big cities, according to U.S. Census data.

The Associated Press examined county-by-county data for 2011, the most recent year available. The numbers show the uphill climb facing President Barack Obama’s health care overhaul in Missouri, which opted against setting up its own exchange and instead allowed the federal government to run it.

Missouri overall ranks right in the middle of the nation in the percentage of uninsured residents under age 65 — tied with Washington state at 25th with 16 percent uninsured. But in 34 of Missouri’s 115 counties, one-fifth to one-quarter of non-senior residents lack health insurance. Twenty-seven of those 34 counties have fewer than 25,000 residents.