Since 2007, foreclosures have dominated real estate news.  You can't turn on the news or open a paper without some foreclosure-related story. 

But for all of the discussion, foreclosures continue to be geographically concentrated. 

Adding up the latest stats from RealtyTrac.com, more than half of the country's foreclosure actions from March occurred in just 3 states -- California, Florida and Nevada.

Those 3 states represent just 19 percent of the nation's population.

Despite the local concentration of foreclosures, however, they remain a national problem.  This is because mortgage lenders lend in all 50 states -- not just 3 of them -- so the impact of mortgage defaults in one region can quickly spread to others.

In part because of foreclosures are higher, the following has happened:

• Mortgage guidelines have tightened
• Downpayment requirements have increased
• Private mortgage insurance has become more expensive

That's an important set of changes for a would-be borrower.  In some cases, it can keep a person from qualifying.