Portland, Nov 2 : Portland Public Schools teachers have launched a strike that has shuttered all its 81 schools in the largest city of the US state of Oregon. The strike, the first in school district history, comes after a 10-month stalemate between district and union leaders as they were unable to agree on even basic budget realities, reports Xinhua news agency. Rallies broke out at most Portland Public Schools campuses starting early Wednesday. The two sides will not meet to negotiate until Friday, which means schools will also close on Thursday. Union leaders say teachers need large raises to keep pace with inflation, class size limits to allow them to meet students' academic and emotional needs, and more planning time to adjust instruction to widely varying achievement levels, according to a report by the Oregonian. Portland Public Schools is contending with enrollment declines driven by low birth rates and high housing prices, the report said. Oregon State Governor Tina Kotek called for the two sides to remain at the bargaining table and continue to negotiate, instead of striking. /IANS