After three decades of progress in closing black-white achievement gaps, these gaps widened during the 1990s and 2000s.  A number of potential explanations remain underexplored, such as how more macro-level policies and sorting mechanisms contribute to black-white achievement gaps.  In this research, we examine the effects of changes in racial differences in the distribution of teacher quality, racial differences in poverty rates, school segregation, accountability pressure, and school funding on changes in black-white test score gaps. We use 2001 through 2010 test score and related data from multiple cohorts of students in grades 3 through 8 in North Carolina, a state with a wide mix of rural, suburban, and urban areas, as well as different school assignment policies in two of the largest school districts:  Charlotte-Mecklenburg and Wake County. The test scores come from vertically equated end-of-grade tests linked to the state-wide curriculum.  We address our questions from a district-level perspective, thus we aggregate student-level data to obtain district-by-year data.  Preliminary results suggest that overall black-white achievement gaps decreased in North Carolina during this period.  These gaps are largest in districts with the largest black-white teacher quality gaps, largest black-white poverty gaps, most segregated schools, most funding, and fewest schools failing AYP.  The largest effect on changes in the black-white achievement gap over time is due to racial differences in teacher quality.  Achievement gaps close faster when blacks have better access to high quality teachers.