I have found there are two easy ways to zero in on open positions for teachers. Using websites like careerbuilder or monster are the quickest but may also yield the least useful results. I am searching for positions in Texas and I have found that by going to the state school board website you can find links to each individual school district and the positions they are looking for.
Many states offer reciprocity for teachers who are certified in neighboring states but I do not know if it is universal.