Home affordability moved higher last quarter, boosted by the lowest mortgage rates in history, a rise in median income, and slow-to-recover home prices throughout Illinois and the country.

According to the National Association of Home Builders, the quarterly Home Opportunity Index read 75.9 in 2011′s fourth quarter. More than 3 in 4 homes sold between October-December 2011, in other words, were affordable to households earning the national median income of $64,200.

Never in recorded history have U.S. homes been as affordable on a national level. Even on a regional and local level, affordability soared.

Affordability was highest in the Midwest; 7 of the 10 most affordable markets nationwide were in the nation’s heartland. 

The Top 5 most affordable U.S. cities in Q4 2011 were:

1. Kokomo, IN (99.2% home affordability)
2. Fairbanks, AK (97.5% home affordability)
3. Cumberland, WV (96.9% home affordability)
4. Lima, OH (96.0% home affordability)
5. Rockford, IL (95.5% home affordability)

These are each considered “small markets”. The most affordable “major market” was the Youngstown, Ohio area, where 95.1% of homes sold were affordable to households earning the area’s local median income.

Not surprisingly, America’s “least affordable cities” were regionally-concentrated, too, with 7 of the 10 least affordable markets located in either California or Texas.

San Francisco (#3), Santa Ana (#4), and Los Angeles (#5) led for the Golden State but, for the 15th consecutive quarter, the New York metropolitan area took “Least Affordable Market” honors.

Just 29 percent of homes in and around New York City were affordable to households earning the area’s median income last quarter. It’s a large jump from the quarter prior during which 23 percent of homes were affordable.

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

In the housing market, amenities and location have as much to do with a home’s value as the everyday forces of supply-and-demand. Whereas the latter causes home values to rise and fall over time, the former creates a starting point for said values. 

Where you live — and the features of your home — determine your home’s price range. Naturally, homes in some areas are consistently higher-valued than homes in others.

Using data compiled by real estate market data firm Altos Research, Forbes Magazine presents America’s 10 most expensive ZIP codes. California and the New York Metro area dominate the list.

1. Alpine, NJ (07620) : $4,550,000
2. Atherton, CA (94027) : $4,295,000
3. Sagaponack, NY (11962) : $3.595,000
4. Hillsborough, CA (94010) : $3,499,000
5. Beverly Hills, CA (90210) : $3,469,891
6. New York, NY (10012) : $3,392,574
7. New York, NY (10013) : $3,317,962
8. Water Mill, NY (11976) : $3,300,000
9. Montecito, CA (93108) : $3,099,348
10. Old Westbury, NY (11568) : $3,095,000

In fact, of the top 50 most expensive ZIP codes, only 6 are located outside of California and New York regions. 3 are Colorado resort towns — Snowmass (81654), Aspen (81611) and Telluride (81435) — one is in Maryland, one is in Florida, and the last is in Washington State.

Chicago-suburb Kenilworth (60043) is the top-ranked Midwest ZIP code. It placed 86th overall.

The Forbes list may be interesting but, to home buyers or sellers in Chicago , it should not be the final word in home values. Real estate is a local market which means that — even within a given ZIP code — prices can vary based on street and neighborhood.

Look past general data and get specific. Talk to your real estate agent for local market pricing.

As 2009 was ending, the “experts” were busy making forecasts about the U.S. economy and what to expect in 2010.

With respect to the housing markets, two predictions were made again and again:

1. Home prices would fall in the first half of 2010
2. Mortgage rates would be higher in 2010

Well, it’s July 1 and the year is half-over.  Both predictions are proving to be incorrect. Home values are rising in most markets and mortgage rates are down. Way down. 

It reminds us that economists are much more skilled with analysis of the past versus predictions of the future.

A pile of data can only get you so far.

Think of Chicago housing market predictions like watching a local weather forecast. A meteorologist can look at the radar and tell you that rain is coming, but it’s never with 100% certainty.  There is always a chance of change.

The housing market is the same way.  Just as the U.S. economy is unpredictable, so are housing prices, and so are mortgage rates. 

Therefore, when you have a personal finance decision to make, evaluate your options based on the information at hand today rather than an educated guess about the future. The future, after all, is subject to change — despite what the experts forecast.