HOUSING : State Tops List of Least Affordable Housing : Real estate: The best buys are in Michigan, Texas, Colorado and New Hampshire, a home builders’ survey finds.

People living in Jackson, Mich., enjoyed the most affordable housing in America as summer began, according to a survey released Tuesday by the National Assn. of Home Builders.

Those shopping for homes outside the Midwest might look at the Brazoria, Tex., area in the South; or Greeley, Colo., in the West, or Nashua, N.H., in the Northeast. They were the most affordable in their regions.

Pass San Francisco, however. It was the most expensive metropolitan area in the home builders’ survey. The least affordable cities in other regions were Chicago in the Midwest; El Paso, Tex., in the South, and New York in the Northeast.

Jackson scored 91.1 on the Home Builders’ housing affordability index. That meant that 91.1% of the homes sold during the second quarter could have been purchased at prevailing interest rates by a family earning the area’s median income.

The median income in Jackson during the April-June period was $36,800, and the median home price was $59,000. The median means that half of the families earned more and half less, or that half of the homes cost more and half less.

According to the mortgage underwriting standards used for calculating the index, a family could afford to purchase a home costing three times its annual income, or in this case, $110,400. The calculation used a prevailing interest rate of 8.42%.

In Jackson, 91.1% of the homes sold during the first quarter were priced at or below $110,400. Brazoria scored 90.9; Greeley, 82.2, and Nashua, 87.1.

San Francisco, on the other hand, scored just 6.7; Los Angeles, 14.7%; Chicago, 66.8; El Paso, 51.8, and New York, 17.6.

The association analyzed 327,977 sales of new and previously owned homes in 173 metropolitan areas for its latest index. The home price data was collected from court records, while the income data was calculated by the Department of Housing and Urban Development.

The survey found that the purchasing power of a typical American family to buy a home improved during the second quarter, although the national median income of $36,800 and the median price of $105,000 remained unchanged from the previous period.

“Households earning the national median income were able to afford to buy 55.5% of the homes offered for sale nationwide, up from 53.9% in the first quarter,” said Robert (Jay) Buchert, the association’s president.

“The jump in affordability was due primarily to the combination of falling interest rates and stable home prices.”

Regionally, trends were also unchanged, with the most affordable markets in the Midwest and South and the least affordable in the Northeast and West, particularly California.

Indeed, 19 of the 25 least affordable areas in the country were in California. The other four were in the Northeast. On the other hand, 18 of the most affordable areas were in the Midwest, four were in the South and three in the Northeast.

Housing Affordability

Here are the 25 most affordable and 25 least affordable U.S. housing markets for the second quarter of 1992, according to the National Assn. of Home Builders. The number corresponding to each area is the percentage of homes sold that were within reach of the median-income household at the prevailing mortgage interest rate.

MOST AFFORDABLE

City Pct. Jackson, Mich. 91.1 Brazoria, Tex. 90.9 Lincoln, Neb. 90.7 Lima, Ohio 89.9 Elkhart-Goshen, Ind. 89.7 Kansas City, Mo.-Kan. 89.5 Lorain-Elyria, Ohio 88.3 Battle Creek, Mich. 88.1 Amarillo, Tex. 88.0 Lansing-E. Lansing, Mich. 87.9 Saginaw-Bay City, Mich. 87.5 Omaha, Neb. 87.5 Grand Rapids, Mich. 87.3 Nashua, N.H. 87.1 Manchester, N.H. 86.9 Daytona Beach, Fla. 86.3 Milwaukee, Wis. 86.2 Youngstown-Warren, Ohio 86.1 Binghamton, N.Y. 85.8 Detroit, Mich. 85.1 Kalamazoo, Mich. 85.1 Lakeland-Wntr Hvn, Fla. 85.0 Muskegon, Mich. 84.7 Dvenprt-Rck Isl., Iowa-Ill. 83.7 Toledo, Ohio 83.1

LEAST AFFORDABLE

City Pct. San Francisco 6.7 Salinas-Seasde-Mntry 11.8 Santa Cruz 13.4 Los Angeles-Long Beach 14.7 Oxnard-Ventura 15.4 Santa Rosa-Petaluma 16.5 Honolulu 17.1 Vallejo-Fairfld-Napa 17.4 New York 17.6 Stockton 19.7 San Diego 19.8 Anaheim-Santa Ana 21.6 Stamford, Conn. 22.5 Oakland 23.2 Santa Barbara-Lompoc 23.2 San Jose 23.8 Merced 27.0 Jersey City, N.J. 29.5 Sacramento 30.0 Riverside-San Brndino 33.0 Chico 34.5 Modesto 36.8 Fall River, Mass.-R.I. 37.6 Redding 39.0 Las Vegas 41.5