Many enslaved people escaped the North Star to freedom, crossing hundreds of dangerous miles until they reached Canada. But thousands also traveled the underground railroad to Mexico, swimming across the Rio Grande to earn their freedom. Mexico outlawed slavery in 1829, declaring that anyone who reached Mexican soil was automatically free. For enslaved people in the Deep South and Texas, reaching Mexico was often easier than traveling to Canada - though both routes promised danger to those who were caught.
Mexico actively helped slaves who escaped, refusing to sign a fugitive slave agreement with the United States. Angry slaveholders ignored the law and hired bounty hunters to cross the border into Mexico to hunt down former slaves. Just like the fugitive slaves in the Great Dismal Swamp, escapees made a new life in Mexico. One former slave even became a millionaire and moved back to the US, claiming to be Mexican.
Brave Americans and Mexicans shepherded escaped slaves across the southern border. Enslaved people risked their lives to float across the Rio Grande on bales of cotton. And one former enslaved person even joined the Mexican military to defend his freedom.
In July 1863, three escaped slaves crossed the wide Rio Grande River, floating on a bale of cotton. Texas newspapers spread the news, warning slaveholders that enslaved people had found a new route to freedom: Mexico.
Others crossed the southern border on foot or hopped ferries that landed in Mexico. Up to 10,000 enslaved people escaped on the underground railroad to Mexico before the US officially outlawed slavery in 1865 with the 13th Amendment.
In the 1850s, the border with Mexico was dotted with military forts, holdovers from the Mexican-American War. American officials at the forts were ordered to capture enslaved people that tried to escape across the Rio Grande. These officials would then return the slaves to slaveholders.
The thousands who successfully escaped to Mexico had to avoid the dangers of the military forts. However, enslaved people who crossed into Mexico often found support from Mexicans who helped the former slaves avoid recapture near the border.
Sam Houston was president of the Republic of Texas and a hero of the Texas Revolution. He was also a slaveholder who enslaved a man named Tom Blue.
Tom was Houston's coachman before he escaped to Mexico and earned his freedom. Once he became free, Tom joined the Mexican military, Houston's old rivals, to protect the country that granted him freedom.
The Fugitive Slave Act of 1850 gave slaveholders the power to force free states to return escaped slaves. Abolitionists fought against the act, declaring it a form of kidnapping.
As thousands of enslaved people escaped to freedom across the southern border, slaveholders pressured Mexico to sign a fugitive slave treaty. The agreement would have forced Mexico to return escaped slaves.
Mexico refused, declaring that on Mexican soil, all enslaved people became free. That didn't stop some Texans from illegally crossing the border to grab former slaves.