Home affordability slipped slightly last quarter, dragged down by rising mortgage rates and recovering home prices in San Francisco Bay Area and nationwide.

The National Association of Home Builders reports a Q2 2011 Home Opportunity Index reading of 72.6. This means that nearly 3 of 4 homes sold last quarter were affordable to households earning the national median income of $64,200.

Q2 2011 marks the 10th straight quarter — dating back to 2009 — in which the index surpassed 70.

Prior to 2009, the index had never crossed 70 even one time.

However, we must remember that the Home Affordability Index is a national survey. From region-to-region, and town-to-town, home affordability varied.

In the Midwest, for example, affordability was highest. 14 of the 15 most affordable markets nationwide were spread throughout Ohio, Michigan, Illinois and Indiana. Only Syracuse (#9) cracked the list from other regions. 

The top 5 most affordable cities in Q2 2011 were:

1. Kokomo, IN (95.8%)
2. Wheeling, WV (94.7%)
3. Lansing, MI; East Lansing, MI (94.4%)
4. Bay City, MI (94.3%)
5. Youngstown, OH; Warren, OH; Boardman, OH (93.7%)

By contrast, the Northeast Region and Southern California ranked as the least affordable markets. Led by the New York-White Plains, NY-Wayne, NJ area, 7 of the 10 least affordable areas were in New York, New Jersey, and California. For the 13th consecutive quarter the New York metro area was ranked “Least Affordable”.

Just 25.2 percent of homes were affordable to households earning the area median income there.

The rankings for all 225 metro areas are available for download on the NAHB website.

Home affordability moved higher last quarter, buoyed by stable mortgage rates and falling home prices in Northern California and nationwide. The National Association of Home Builders reports that Q1 2011 Home Opportunity Index reached an all-time high for the second straight quarter last quarter.

Nearly 3 of 4 homes sold between January-March 2011 were affordable to households earning the national median income of $64,400. It’s the 9th straight quarter in which home affordability surpassed 70 percent, and the highest reading in more than 20 years of record-keeping.

From metropolitan area-to-metropolitan area, though, affordability varied.

In the Midwest, for example, affordability was high. 7 of the 10 most affordable markets were in the Midwest, including Kokomo, Indiana, in which 98.6% of homes were affordable to median income-earning families. Indianapolis, Indiana placed second for “big city” affordability.

The most affordable “big city” last quarter was Syracuse, New York. With a 94.5% affordability rate, Syracuse ranks 8th nationally in the Home Opportunity Index. It’s the second time that Syracuse placed first in the last 4 quarters.

Meanwhile, on the opposite end of home affordability, the “Least Affordable Major City” title went to the New York-White Plains, NY-Wayne, NJ area for the 12th consecutive quarter. Just 24.1 percent of homes were affordable to households earning the area median income, down more than 1 percent from the last reading.

Regardless of where you live, remember that rising mortgage rates can levy more pain on your household budget than can rising home values. And mortgage rates are expected to rise long before home prices do.

The rankings for all 225 metro areas are available for download on the NAHB website.