From the mid 19th to 20th centuries, many black people and ethnic Mexicans intermarried with each other in the Lower Rio Grande Valley in South Texas (mostly in Cameron County and Hidalga County). In Cameron County, 38% of black people were interracially married (7/18 families) while in Hidalgo County the number was 72% (18/25 families). These two counties had the highest rates of interracial marriages involving at least one black spouse in the United States. The vast majority of these marriages involved black men marrying ethnic Mexican women or first generation Tejanas (Texas-born women of Mexican descent). Since ethnic Mexicans were considered white by Texas officials and the U.S. government, such marriages were a violation of the state's anti-miscegenation laws. Yet, there is no evidence that anyone in South Texas was prosecuted for violating this law. The rates of this interracial marriage dynamic can be traced back to when black men moved into the Lower Rio Grande Valley after the Civil War ended. They married into ethnic Mexican families and joined other black people who found sanctuary on the U.S./Mexico border.