Were the people living in Mexican territories annexed by the US in the Mexican-American War given citizenship?

by ChickenpoxForDinner

If not was there a 'fast track' to American citizenship at all?

RioAbajo

Short answer is yes, the Treaty of Guadalupe Hidalgo was signed in 1848, ending the Mexican-American War and giving all former Mexican citizens in the new US territories full US citizenship. Alternatively, the option was provided that if they migrated to within the new Mexican borders they could retain their Mexican citizenship.