The OP is not completely ludicrous, but I expect that the effect would be small.
By the way, while migration is typically thought to be driven by job considerations, non-economic factors can play a measurable role as well:
Yeah, I grew up in the South and when I was very young a lot of civil rights protests and such were happening. At the time I was too young to really know anything about it, I knew that blacks had different color skin than me, and for some reason that meant they were different and that different rules applied to them. I understood the civil rights movement was them not liking that.
I asked my dad one day after watching the news why they didn’t just move to another state, wouldn’t that be easier than what they were doing? His response was more or less to the effect of, “They’re southerners too, why would they want to leave their home?”
Nope, people tend to move either for economic reasons or because other factors forced them to move. (Disaster, war, etc.) You might find a hand full of people who will move, for example I actually know someone who moved to New Zealand because he hates George Bush, but for the most part people will go where the money is.
Abortion is but one political issue in the United States and one that is overblown in my opinion. I don’t think most people consider the question of abortion to be all that important to their own lives but it’s a hot button issue among some so it gets more press than deserved.
Marc