As of 2005, Maine has an estimated population of 1,321,505, which is an increase of 6,520, or 0.5%, from the prior year and an increase of 46,582, or 3.7%, since the year 2000. This includes a natural increase since the last census of 6,413 people (that is 71,276 births minus 64,863 deaths) and an increase due to net migration of 41,808 people into the state. Immigration from outside the United States resulted in a net increase of 5,004 people, and migration within the country produced a net increase of 36,804 people.

Maine is a popular tourist destination, but it also experiences harsh winters and, consequently, the great temporary influx of visitors occurs during the warmer months. Many of these visitors establish an alternate secondary residence in Maine during some or all warm months and then depart for their primary residence in the off-season. These are the summer people of Maine lore. Official census figures normally count a person as a resident only once, at the place of the primary home. Therefore, there are some situations in which official census figures could be misleading for Maine. For example, some communities may have a much larger seasonal retail sector than their official, small population figure would imply.

The center of population of Maine is located in Kennebec County, in the city of Augusta [2]. However, as explained in detail under "Geography", there are large tracts of uninhabited land in some remote parts of the interior.