That sums it up nicely and yes - you are right. It is the culture here that makes the difference. The south is socially and culturally conservative and has consistently been so for quite some time.
Some call it the "bible belt," though religion is only a part of the equation. It is a big one though and church membership trends show it. I recently read a sociology report on church membership stats that broke down protestant denominations as they relate to moral ideology then followed the statistical growth/decline of their membership over the last few decades.
"conservative" denominations included Baptists, Mormons, Seventh Day Adventists, Pentecostals, certain branches of Lutherans, and various other evangelical, fundamentalist, and conservative non-denominational protestants. They are strongly represented in the south and the west.
"mainstream" denominations included Methodists, Episcopalians, and Presbyterians. They are represented nationally, though somewhat stronger in the east.
"liberal" denominations included Unitarians and whatnot. They are represented in the northeast.
Trends indicated that the "conservative" churches had rapidly gained membership in recent decades. The "mainstream" churches were all stagnant in membership, or had slight gains or declines. The "liberal" denominations were at best stagnant and at worst lost members. The stats suggest that religion is currently strongest in the south and west and has been growing stronger in these regions for several decades. So a reversal in which the south becomes socially liberal does not seem likely at any time in the near future.