Lake types:

Glacial Lakes
Most of North America's lakes including the Great Lakes were formed during the most recent cycle of glacial activity (approx. 10,000 to 20,000). Although glaciers can form lakes through several unique processes, most basins are carved out by the glacier's weight and movement, or created when glacial debris forms dams. Glacial moraine dams are responsible for a number of lakes in North America (e.g., Lake Mendota in Wisconsin). Melting ice blocks left by retreating glaciers create kettle lakes (e.g. Walden Pond in Massachusetts).

Tectonic Basins
These basins form or are exposed due to movements of the earth's crust. This can result from uplifting as when irregular marine surfaces that collect freshwater after elevation (e.g. Lake Okeechobee in Florida), and tilting or folding to create depressions that form lake basins (e.g. Lake Champlain along the New York Vermont border). Lakes also form along faults (e.g. several lakes in California).

Other processes of lake formation are generally less common, but responsible for the wide variety of lakes that we see across North America. Examples include:

Volcanic Lakes
Several different volcanic processes can form lake basins. Craters form natural basins (Crater Lake in Oregon) well-known for their clear waters and lava dams can create basins in valleys.

Landslide
Rockfalls or mudslides that dam streams or rivers can form lakes for periods as short as a year to several centuries (e.g. several lakes in the Warner Range of northeastern California).

Solution Lakes
These lakes can be found in areas characterized by significant limestone deposits where percolating water creates cavities. These lakes are particularly common in Florida.

Plunge pools
Although somewhat rare, these lakes were formed when ancient waterfalls scoured out deep pools. They are often associated with glacial activity that diverted river flow (examples are Falls Lake in Washington and Green Lake in New York)

Oxbow Lakes
Where rivers or streams have meandered across low gradients, oxbows can often form in areas where the former channel has become isolated from the rest of the river. Several examples can be found along the Mississippi River and other large rivers.

Beaver-made and human-made lakes
Both humans and beavers create lakes when they dam rivers and streams. Lake Mead and Lake Powell are two of the more dramatic examples of human-made lakes along the course of the Colorado River. In addition to the many large dams, there are upwards of one million small dams impounding lakes and ponds across the lower 48 states.