Eastlake was created in 1911 by the Eastlake Investment Company when they divided 31.5 acres to create a subdivision which would include four streets and 886 lots.  It is one of the oldest townships in the northern Denver area. It is also home to the Stargate Charter School which was erected in 1908 and was the first schoolhouse in what is known now as the Adams District 12 school district.

Development of this historic area was pushed mostly by the proximity to the Union Pacific Railroad and agriculture.  The rail helped area farmers move cucumbers, grain and cattle.  The Farmers Cooperative Grain Elevator was built in 1920 near the rail to further assist in transporting grain. While the area depending on the rail heavily, farmers were also dependant on the three Easlake Reservoirs to provide water for the crops and recreational opportunities such as fishing and swimming.  It is said that Reservoir III was originally a buffalo wallow before being dammed for irrigation.

Eastlake was eventually annexed into the City of Thornton in order for the small community to upgrade failing septic systems.  Once, annexed, Eastlake saw the benefits of hooking of to city sewer systems and becoming part of a master plan community.  However, steps were taken to help ensure that the character and historical value of this community have been preserved.