It depends on which part of Texas and which part of Louisiana you mean. Every part of Louisiana is further south than some parts of Texas, but there are also parts of Texas that are further south than any part of Louisiana.
There are probably more than one Hopewell Plantation in Louisiana, but Hopewell Plantation in South Louisiana was in East Feliciana Parish, south of Jackson, La. It is no longer in existence but was South of Jackson, La between what is now Hwy. 68 and Thompson Creek.
The only state of the US that's completely south of 30 degrees south atitude is Hawaii. Florida, Louisiana, and Texas also have some portion of their territory south of that latitude. Louisiana and Texas are both mostly north of it.