(a) Except as hereinafter provided, the governing body of any city, by ordinance, may annex land to such city if any one or more of the following conditions exist:

(1) The land is platted, and some part of the land adjoins the city.

(2) The land adjoins the city and is owned by or held in trust for the city or any agency thereof.

(3) The land adjoins the city and is owned by or held in trust for any governmental unit other than another city except that no city may annex land owned by a county without the express permission of the board of county commissioners of the county other than as provided in subsection (f).

(4) The land lies within or mainly within the city and has a common perimeter with the city boundary line of more than 50%.

(5) The land if annexed will make the city boundary line straight or harmonious and some part thereof adjoins the city, except no land in excess of 21 acres shall be annexed for this purpose.

(6) The tract is so situated that 2/3 of any boundary line adjoins the city, except no tract in excess of 21 acres shall be annexed under this condition.

(7) The land adjoins the city and a written petition for or consent to annexation is filed with the city by the owner.

(b) No portion of any unplatted tract of land devoted to agricultural use of 21 acres or more shall be annexed by any city under the authority of this section without the written consent of the owner thereof.

(c) No city may annex, pursuant to this section, any improvement district incorporated and organized pursuant to Kan. Stat. Ann. § 19-2753 et seq., and amendments thereto, or any land within such improvement district. The provisions of this subsection shall apply to such improvement districts for which the petition for incorporation and organization was presented on or before January 1, 1987.

(d) Subject to the provisions of this section and Kan. Stat. Ann. § 12-520a(e), and amendments thereto, a city may annex, pursuant to this section, any fire district or any land within such fire district.

(e) No city may annex the right-of-way of any highway under the authority of this section unless at the time of the annexation the abutting property upon one or both sides thereof is already within the city or is annexed to the city in the same proceeding. The board of county commissioners may notify the city of the existence of the right-of-way of any highway which has not become part of the city by annexation and which has a common boundary with the city. The notification shall include a legal description and a map identifying the location of the highway. The governing body of the city shall certify by ordinance that the certification is correct and declare the highway, or portion of the highway extending to the center line where another city boundary line abuts the opposing side of the highway, annexed to the city as of the date of the publication of the ordinance.

(f) The governing body of any city by one ordinance may annex one or more separate tracts or lands each of which conforms to any one or more of the foregoing conditions. The invalidity of the annexation of any tract or land in one ordinance shall not affect the validity of the remaining tracts or lands which are annexed by the ordinance and which conform to any one or more of the foregoing conditions.

(g) No city may utilize any provision of this section to annex a narrow corridor of land to gain access to noncontiguous tracts of land. The corridor of land must have a tangible value and purpose other than for enhancing future annexations of land by the city.