The Choptank quadrangle lies between parallel 38° 30' and 39° north latitude and meridians 76° and 76° 30' west longitude. It includes one-fourth of a square degree of the earth's surface and contains 931.51 square miles. From north to south it measures 34.5 miles and from east to west its mean width is 27 miles, as it is 27.1 miles wide along the southern and 26.9 miles along the northern border.