The Rio Grande, Sabine, and Red Rivers are similar in that they are- Natural political boundaries
Major shipping lanes
Connected to the Canadian River
Man-made transportation routes

the california missions began in the late 18th century as an effort to convert native americans to catholicism and expand european territory. there were 21 missions in all, lasting from 1769 until about 1833.   the missions were built by the spanish starting in 1769 in order to “colonize” the territory of alta california. so the missions were important because they were the means of settling california. it also wanted to keep other european countries out of alta california. building settlements along the coast would them meet these goals. missionaries wanted to convert the indians to the roman catholic faith. california indians did much of the work to build missions.

they wanted the u.s. to fight on the side of the central powers.