Drug trafficking has little to do with the border issue, since you cannot really do anything about it when you have thousands of miles of border to secure. The issue here is how much corruption exists in the US and how little it does against the really big criminals who control traffic.

The justice system concentrates only on putting small vendors behind bars (usually black people), but they're not the ones making real profits. I guarantee you don't know any big drug traffickers operating inside the US that were sent to jail. When you hear about big bosses it is always some guy outside the US, but the ones operating inside the country are all protected in one way or another. They're all laughing and buying mansions all over the country. This corruption is what the US should be concentrating on if they want to stop drug trafficking.