Section 1. The state is authorized to engage in the construction, improvement, repair and maintenance of public roads, highways, and bridges in the state of Alabama. To this end, and for this purpose, the state is authorized to appropriate funds; and also to issue and sell interest-bearing negotiable state bonds, in an amount not to exceed the sum of twenty-five million dollars ($25,000,000.00) to be issued in such denominations, numbers, and series, and maturing at such time, as may be provided by law; but such bonds shall bear a rate of interest not greater than six per centum per annum, payable semi-annually, and shall be sold at a price not less than the par value thereof. Provided, that no bonds shall be issued or sold under this provision to such an amount that the interest thereon will exceed the net amount of vehicle license tax collected for the year preceding the issuance of same, and which is set apart for the payment of interest on said bonds. The state highway commission or highway department shall locate, construct, and maintain highways and state trunk roads so as to connect each county seat with the county seat of the adjoining county by the most direct or most feasible route, or by a permanent road, having due regard to the public welfare, and to connect the county seats of the several border counties at or near the state line with a public road in the border states. Provided, that in counties which are divided into two or more judicial divisions in each of which regular terms of circuit court are held; the places where said terms of court are held shall likewise be connected with each other. It shall be the duty of said highway commission or highway department to equitably apportion among the several counties the expenditure of both money and labor and the time or times of making such investments. Not less than one-quarter of a million dollars of the proceeds of these bonds shall be set aside and expended by the state highway commission in each county in the state. To create a sinking fund for the prompt and faithful payment of the principal and interest on these bonds and for the construction, maintenance, and improvement of such public highways, roads, and bridges, the legislature shall levy a special annual license or privilege tax on all automobiles, and on all motor driven vehicles which may be used on the public roads and highways of this state. Such bonds when issued shall be a direct obligation of the state, and for the prompt and faithful payment of the principal and interest thereon the full faith and credit of the state is hereby irrevocably pledged, and such bonds shall be exempt forever from all taxes of every kind.