When did the first people arrive in America?

Some say the vikings around 700 AD .Most hold to the fact that native Americans were here before Christ was born . Most history books say that John Smith( yeah like pocahontases father believed that name) set up the first settlement in 1607 at now named Jamestown. The Mayflower bunch arrived 13 years later at Plymoth Rock in Massachuetts. According to the James Michner book Mexico people arrived in the southwest from Mexico in the 1500s. My money goes with Michner . He wrote books with such detail and research it is no wonder that all his books average approx. 1200 pages. __________________________ The Bering land bridge was a land bridge roughly 1,000 miles (1,600 km) north to south at its greatest extent, which joined present-day Alaska and eastern Siberia at various times during the Pleistocene ice ages. It was not glaciated because snowfall was extremely light due to the southwesterly winds from the Pacific Ocean having lost their moisture over the fully glaciated Alaska Range. The grassland steppe including the land bridge and stretching for several hundred miles either side of it has been called Beringia. It is believed that a small human population of at most a few thousand survived the last ice age in Beringia, isolated from its ancestor populations in Asia for at least 5,000 years, before expanding to populate the Americas sometime after 16,500 years ago, as the American glaciers blocking the way southward melted. The Bering land bridge is significant for several reasons, not least because it is believed to have enabled human migration to the Americas from Asia about 25,000 years ago. A study by Hey (2005) have indicated that of the people migrating across this land bridge during that time period, only 70 left their genetic print in modern descendants, a minute effective founder population-easily misread as though implying that only 70 people crossed to North America. Seagoing coastal settlers may also have crossed much earlier, but scientific opinion remains divided on this point, and the coastal sites that would offer further information now lie submerged in up to a hundred metres of water offshore. Land animals were able to migrate through Beringia as well, bringing mammals that evolved in Asia to North America, mammals such as proboscideans and lions, which evolved into now-extinct endemic North American species, and allowing equids and camelids that evolved in North America (and later became extinct there) to migrate to Asia. A new study published November 26, 2007 (see PLoS Genetics), which was led by University of Michigan and University College London researchers, seems to suggest that the Bering land bridge migration occurred during one specific time period which was 12,000 years ago, that every human who migrated across the land bridge all came from Eastern Siberia during that time period, and that every native American is directly descended from that same group of Eastern Siberian migrants. The claim suggests that a "unique genetic variant widespread in natives across both continents - suggesting that the first humans in the Americas came in a single migration or multiple waves from a single source, not in waves of migrations from different sources".