Barriers to the cross-state mobility of the teacher workforce can have undesirable effects on the teacher workforce and student outcomes. While a large literature addresses issues related to within-state mobility, very little is known about patterns of cross-state mobility. This paper addresses that research gap. We describe features of Oregon's and Washington's teacher labor markets that impose barriers to mobility and use state administrative data sets to identify teachers who have crossed the state border. Large disparities between levels of within-state and cross-state mobility are evidence of significant barriers to mobility between Oregon and Washington. In fact, teachers are over four times more likely to undertake a within-state move of 250 or more miles than they are to undertake a cross-state move of any distance. Even teachers employed in a district on the state border are at least as likely to move 225 or more miles within their state as they are to move across the border. Observed patterns of cross-state mobility are consistent with some of the variation in costs imposed by licensure procedures, seniority rules, and pension structures. In particular, less experienced teachers are significantly more mobile. However, we observe a similar pattern in regard to "within"-state mobility, suggesting that fewer experienced teachers cross state borders because they are less mobile in general, and not necessarily because they face higher costs to cross-state mobility in particular. More nuanced analyses is required to better understand the mechanisms driving low rates of cross-state mobility. Two appendices provide: (1) Entry Level Salaries for Teachers with a Bachelor's Degree (2013) [figure]; and (2) Pension Wealth in Oregon and Washington.