The relative progress of Maryland has been slow indeed. The population of the Union, by the census of 1790, was 3,929,827, of which Maryland, containing then 319,728, constituted a twelfth part (12.29). In 1860, the Union numbered 31,445,080, and Maryland 687,034, constituting a forty-fifth part (45.76). In 1790, the free States numbered 1,968,455, Maryland's population then being equal to one sixth (6.12); but, in 1860, the population of the free States was 18,920,078, Maryland's number then being equal to one twenty-seventh part (27.52). But, if Maryland had increased as rapidly from 1790 to 1860 as the whole Union, her proportion, one twelfth part, would have made her numbers in 1860, 2,620,315; and if her proportional increase had equalled that of the free States, her ratio, one sixth, would have made her population in 1860, 3,153,392. She might not have reached either of these results; but, before closing these articles, it will be proved that, in the absence of slavery, her population, in 1860, would have been at least 1,755,661, or the same per square mile as Massachusetts; and Baltimore, bearing the same ratio to this number as to Maryland's present population, would have contained in 1860, 542,000, instead of 212,000, her present number. I take the areas from the able report (November 29, 1860) of the Hon. Joseph S. Wilson, then Commissioner of the General Land Office, where they are for the first time accurately given, 'excluding the water surface.' The population is taken from the census, the tables of 1850 and 1860 being compiled with great ability, by the present superintendent, the Hon. J. C. G. Kennedy. I compare first Massachusetts and Maryland, because they are maritime and old States, and both in 1790 had nearly the same population, but, as will be shown hereafter, with vastly superior natural advantages in favor of Maryland. Area of Maryland, 11,124 square miles; shore line, by tables of United States Coast Survey, viz.: main shore, including bays, sounds, &c., 503 miles, islands 298, rivers to head of tide water 535; total, 1,336 miles. Area of Massachusetts, 7,800 square miles; shore lines, by tables of United States Coast Survey, viz.: main shore, including bays, sounds, &c., 435 miles, islands 259, rivers to head of tide water 70; total, 764 miles. When we mark the Potomac and its tributaries, the lower Susquehanna, the deep and numerous streams of the Chesapeake, the commercial advantages of Maryland over Massachusetts are vast indeed. Looking at the ocean shore of Maryland, and also at the Chesapeake bay, the largest and finest estuary in the world, indented with numerous sounds and navigable inlets, three fourths of its length for both shores being within Maryland, and compare this deep and tranquil and protected basin, almost one continuous harbor, with the rock-bound coast of Massachusetts, lashed by the stormy Atlantic, the superiority of Maryland is striking.