CHULA VISTA, Calif. -

Mexican license plates are common in parking lots of shopping malls in U.S. border cities. Merchants and shoppers say they will be even more familiar after Mexico raises its sales tax in border regions to match the rest of the country.
   
The increase to 16 percent from 11 percent takes effect January 1, 2014.
   
It has sparked large protests on the Mexican side of the border. Facebook pages with secessionist tones have generated about 200,000 "likes." Thousands have signed petitions to challenge the tax hike in court.
   
The Mexican government says the two-tiered tax structure - introduced decades ago to make border cities competitive - is no longer justified. Others say the increase may backfire by driving more shoppers north of the border.