(FORTUNE Magazine) – Every state but North Dakota is now home to at least one Japanese-affiliated factory, most of them wholly owned by a Japanese company, according to a new survey by the Japan External Trade Organization. The government group found that as of September 1991, Japanese companies owned 10% or more of 1,563 plants in the U.S., vs. 1,435 in 1990. Total number of employees in these U.S. factories rose to about 350,000, from 300,000 in 1990. As the map shows, California has the most plants. North Dakota, meanwhile, expects to join the club in 1993. For all this, the trend toward building plants and buying others peaked in the late 1980s as Japanese automakers set up U.S. factories. First-time investments reached $10.6 billion in 1988 but fell to $3.9 billion in 1990. Last year it was probably down again, though the exact numbers aren't available yet. Japanese makers of electric and electronic equipment are proving the most persistent investors. Example: Hitachi Electronic Devices U.S., wholly owned by Hitachi, has begun to turn out cathode ray tubes for TVs at its new plant in Greenville, South Carolina. Other forms of Japanese investment are dropping precipitously. The U.S. Department of Commerce estimates net investment in all U.S. businesses, including banking, fell to $4.3 billion in 1991, compared with about $17 billion in each of the preceding three years. Worldwide, Japan imported more ) long-term capital in 1991 than it exported, the first time that has happened since 1980. The money going home is helping to prop up a weakening economy. Some economists, including FORTUNE's, worry that if, as part of this trend, the Japanese sell their U.S. bonds in great volume, U.S. interest rates could then rise and hamstring the U.S. recovery.

CHART: NOT AVAILABLE CREDIT: FORTUNE MAP/SOURCE: JAPAN EXTERNAL TRADE ORGANIZATION CAPTION: WHERE 1,563 JAPANESE FACTORIES ARE