What started as a simple joint venture between Baltimore's RTKL Associates and a Mexican company has developed into a full-blown sister-state agreement that could accelerate Maryland's growing trade relationship with Mexico. Yesterday's signing of an agreement between Maryland and the Mexican state of Jalisco also offered Gov. William Donald Schaefer a chance to continue his personal campaign for passage of the North American Free Trade Agreement, now pending before Congress. "It's incumbent upon us to do everything we can to have this treaty ratified this year, not four years from now," Mr. Schaefer said. "In Maryland, we see Mexico as a country on the move, as a potential new partner in trade and investment," he added. "That's why signing this sister-state trade agreement is so timely." Mr. Schaefer's comments yesterday were the state's latest public show of support for NAFTA. In August, the agriculture secretaries of Maryland, Delaware and Virginia jointly described the benefits of the trade pact in a statement pushing for its passage. The Jalisco agreement, like similar ones with six other states in Japan, Korea, Poland, Russia, France and China, was intended to open doors for companies looking to do business abroad, "to promote friendly relations, and to enhance cooperation and understanding" in education, culture, environmental protection, agriculture and tourism. It grew out of a joint venture agreement signed in February between the architectural firm RTKL and a Guadalajara architectural firm, Gomez Vazquez Aldana & Asociados. Their first joint project, a Shera ton hotel and condominium on South Padre Island in Texas, is being built by a Mexican developer, according to RTKL Chairman Harold L. Adams. He delivered a letter to Mr. Schaefer from Jalisco Gov. Carlos Rivera Aceves and then helped organize and joined Maryland's economic mission to Jalisco in July. The value of Maryland exports to Mexico increased 44 percent since 1987, to more than $60 million last year, said Mark L. Wasserman, secretary of the Department of Economic and Employment Development. Jalisco is home to operations run by RTKL, McCormick & Co. Inc., Black & Decker Corp. and the Ryland Group Inc.