N.M. Stat. § 67-3-31
Whenever the board of county commissioners of any county desires that any main traveled road or roads in such county included among those adopted by the state transportation commission as a system of state roads shall be improved or constructed under the provisions of Chapter 67 NMSA 1978, written application shall be made by the board of county commissioners to the secretary for such improvement or construction and for state aid therefor. If the board of county commissioners of any county fails to apply for state aid during the year for which such aid is available, that county shall thereby forfeit its right to its portion of state aid for that year, and the funds apportioned to that county for the year shall remain in and be a part of the state road fund for the succeeding year. If upon receipt of such application the state transportation commission is satisfied, after investigation, that the proposed improvement should be made or undertaken and that the county will be able to pay its portion of the cost and that state funds will be available to pay the state's portion of the cost, it may approve the same and undertake such work of improvement in accordance with the provisions of Chapter 67 NMSA 1978. The secretary or one of his assistants shall proceed to view the road or part thereof proposed to be improved and make all surveys, plans, specifications and estimates of cost for its construction out of such materials as may be decided upon by the secretary; provided, that whenever in the judgment of the state transportation commission it is desirable to proceed with the improvement of any road in the system of state roads, for the improvement of which the county commissioners of the county in which the same is located shall have failed or declined to make application as provided in this section, it is lawful for the secretary to proceed with the improvement of any such road without application from the board of county commissioners and to pay the entire cost of such improvement from the portion of the state road fund made available under the provisions of Chapter 67 NMSA 1978 for expenditure wholly within the discretion of the state transportation commission and from the state apportionment of funds under the act of congress referred to in Section 67-3-33 NMSA 1978.
NMS § 67-3-31