What was the negative effect to the underground railroad?

some of the slaves were caught and then hurt or killed

One result was the enactment of the Fugitive Slave Law of 1850. This placed both escaping slaves and freedmen in jeopardy. Some legally-freed people of color were captured and ended up back in slavery.

The refusal of some northern states to enforce this law helped pave the way for the Civil War, since southerners eventually cited the "uncooperative" stance of the North as a reason for secession.

Ultimately, however, I'd say that the Underground Railroad had many more positive than negative effects.



https://en.wikipedia.org/wiki/Fugitive_slave_laws

Well, it didn't run on time....

Just kidding. But it did put escaping slaves at risk. As awful as slavery is, in general the slaves weren't being shot.

Where there negative effects of the underground railroad - yes of course. But in spite of these small problems the underground railroad served many innocent black people to escape from the terrible bondage of slavery.

The underground railroad was the start for blacks who desired to be free, it was the first domino to fall, today all government sanctioned slavery has been eradicated from the world.