(1) After the taking of a United States¹ census showing the population of any school district to be such as to entitle it to be changed from one class of school district to another;

(2) When a district, which at a decennial census, had sufficient population to entitle it to an advance to another class of district, has since suffered a large decrease in population, or which at a decennial census did not have sufficient population to entitle it to an advance to another class of district and has since increased in population, a census of the district may be authorized by the board of school directors of the district, and, if it shall appear that said district has not the required population to remain in the class in which the same then is or if it shall appear that the district has sufficient population to entitle it to advance to another class of district, the Superintendent of Public Instruction,² on the request of the board of school directors and upon receipt of the facts disclosed by said census, may issue his proclamation declaring such district to be of the class to which it properly belongs, as disclosed by the census of the school board.

(3) Where the population of two districts combined subsequent to the taking of a United States census and ascertained by such census is such as to entitle the new or combined district to be in a class different from the class of either of the districts so combined;

(4) Where, since the last preceding United States census, any territory has been annexed to any city, borough, town, or township, whereby the population of such city, borough, town, or township has been increased, and the population of such annexed territory cannot be ascertained from the last preceding census of the United States, the directors of the school districts affected by such annexation may apply to the court of common pleas for the appointment of a commissioner to make an enumeration of the population of such annexed territory. The court shall certify the population of the annexed territory so ascertained, together with the population of the city, borough, town, or township, as shown by the last preceding United States census, to the Superintendent of Public Instruction. The cost of the proceeding, including reasonable compensation for the commissioner, to be fixed by the court, shall be paid by the school district.