All taxes heretofore* assessed, levied or collected by any county, for secondary road construction and maintenance purposes, on real and personal property within cities and towns located in any such county, be and the same are hereby declared to be legal and valid, and where the same have not been paid, the officers of such counties are hereby empowered and directed to proceed at once to collect the same as other taxes are collected and to use the same for authorized secondary road construction and maintenance purposes.