Sonoma County wine mogul Jess Jackson is worth an estimated $1.85 billion, making him the 193rd richest American, according to Forbes magazine.

Jackson?s fortune is down from $2.4 billion last year, when he was No. 187 on the magazine?s list of the 400 Richest Americans.

Jackson owns Jackson Family Wines, which includes Kendall-Jackson and other premium wine brands. Sales of upscale wines slipped over the past year as the economic downturn left consumers with less cash in their pockets.

He was the only Sonoma County resident on the annual list, but two Marin County billionaires made the cut. Filmmaker George Lucas was No. 97 with a $3 billion fortune, while hotel heir Daniel Pritzker was No. 236 with $1.5 billion.

Microsoft co-founder Bill Gates topped the Forbes list with $50 billion, down $7 billion from last year. Investor Warren Buffet was second with $40 billion.