Lesson 1 Commentary: Introduction

As we discuss the development and growth of the United States, it will be helpful for you to open your book to the maps on pages 954–957. North and Central America were at one time covered by vast shallow seas. The land appeared as the waters receded. Earthquakes and the shifting of plates caused uplifts and resulted in the formation of mountains. The earliest mountains were those of the Ozarks, now eroded away and shown on your map as the Ozark Plateau in the center of the United States. The next mountains to develop were the Appalachians to the east, and the youngest mountain range is the Rockies, which extends down the western side of Canada and the United States, then down through Central America to the Andes. The Rocky Mountains become important in America's history because they formed a barrier to western expansion in the United States and because they affected the dispersing of the native Americans and their different lifestyles. In the lower left-hand corner of the map you will see the Bering Sea, which lies between present-day Alaska and Russia. It is there that our history begins.