Proceedings to create an incorporated city under ORS § 222.210 to 222.310 may be initiated by petition signed by not less than 10 percent of the electors of each incorporated city to be included within the proposed city. If it is proposed to include one or more unincorporated areas in the proposed city, the petition shall be signed by not less than 10 percent of the electors registered in each such area at the closing of the registration books by the county clerk at the close of registration preceding the last general election. The areas may be contiguous with one another. [Amended by 1971 c.761 § 2; 1983 c.83 § 24]