The board of county road commissioners of any county bordering on a stream which is the boundary line between such county and a county in another state, is hereby authorized, in conjunction with the proper highway authorities of such adjoining county or state, to construct, rebuild, repair and maintain a bridge, or bridges, across such stream at such place or places within the limits of such boundary as may be agreed upon by said board of county road commissioners and highway authorities, whenever said board of county road commissioners shall deem it necessary, and to enter into a contract with the proper highway authorities of such adjoining county or state relative thereto: Provided, however, That the board of supervisors of such county shall provide by resolution for the raising of funds to pay for the construction, rebuilding, repairing or maintaining of such bridge, or bridges, and for such purposes the board of supervisors of such county may levy a special tax not to exceed 1 mill on the assessed valuation of all the property of such county for such part of the cost of constructing, rebuilding, repairing or maintaining of such bridge, or bridges, as shall be allotted to such county; and such board of supervisors is hereby authorized, at any regular or special meeting of such board, to borrow on the faith and credit of such county, such sums of money as may be needed to carry out the purposes aforesaid, not exceeding the amount specified in this act, and to levy such amount to be collected with the next ensuing assessment.