The memorandum of understanding between the Croatian agency and Riverside will be signed by the agency's director, Sani Ljubicic, and the county supervisor, Marion Ashley, Croatia's consul-general in Los Angeles, Ilija Zelalic, told Hina on Tuesday.
Riverside County, one of California's 58 counties, has a population of 2.1 million.
On Wednesday, the agency's delegation will present Croatia's economy at the World Trade Center in Los Angeles and meet with the center's director, Vance Brougham, and the head of the Los Angeles Chamber of Commerce, Gary Toebben.
The delegation will hold meetings with American businessmen of Croatian origin.
On Thursday, the agency's representatives will visit the Silicon Valley.
California is the largest state economy in the USA, accounting for 13 percent of the USA's Gross Domestic Product.