To navigate the different elevations of the natural terrain, canals were built with locks. The structure consisted of two gated areas in the canal. When a boat entered the lock, the gate would close behind it and the water level would be raised, floating the boat to the higher elevation. When the water level inside the lock equaled that on the other side of the gate, the boat would be released. This 6" x 4" (15.24 by 10.16 cm) photograph shows a boat entering one of the locks near Grand Rapids, Ohio. A second 5.3" x 3.75" (13.34 by 9.53 cm) photograph shows a canal boat leaving one of the locks near Providence, Ohio. The Miami and Erie Canal was built between 1825 and 1848 and extended from Toledo to Cincinnati. Boats shipped cargo along the canal, including bulk agricultural products such as shell corn, wheat, wool, pork, and lard. As an intersection point for Lake Erie and both the Wabash and Erie Canal, which ran west to Indiana, and the Miami and Erie Canal, Toledo played an important role in this type of commerce. The growth of the canal system resulted in a population boom in Toledo and other cities along the canal routes, cheaper shipping costs for farmers, and less expensive goods for consumers.