Question

How did the Spanish extend their Northern Buffer Zone to the West in the 1760s?

Answer 1

The Spanish extend their Northern Buffer Zone to the West in the 1760s as they colonized the California coast. The Spanish were afraid of losing the California coast to Russian traders probing south from Alaska. Thank you for posting I hope it helps. 

Answer 2

The Spanish extended their Northern buffer zone to the West in the 1760's by conquering and colonizating new lands in order to protect their territory of New Mexico. The Spanish influence has transcended in these territories, as nowadays the language and culture could be seen in the people of New Mexico, Arizona and California.