TREATY OBSERVANCE: The anniversary of the 1847 signing of the Treaty of Cahuenga, which was responsible for the acquisition of California by the United States, will be observed today at the Campo de Cahuenga, 3919 Lankershim Blvd., North Hollywood, the treaty's signing place. Admission is free.

SUPERVISOR VISIT: Los Angeles County Supervisor Mike Antonovich will meet with Santa Clarita Valley constituents Monday at Santa Clarita City Hall, Suite 255, from 10 a.m. to 3 p.m.

GANG ORDINANCE: The Los Angeles County Board of Supervisors on Tuesday is scheduled to discuss whether to help the city of San Fernando defend an ordinance that bans gang members from a city park. The ACLU is challenging the ordinance.