Geographic Flag for the Lowest Lake in the USA - The Salton Sea, California: 115 Degrees West by 33 Degrees North

Flag for America's Dead Sea - The Salton Sea.  The colours are coded to numbers, which define the longitude and latitude.

Image Credit - Wikipedia: 
https://en.wikipedia.org/wiki/Salton_Sea#/media/File:Salton_Sea_Reflection.jpg

Geographic Flag for the Highest Point in Alaska at 151 Degrees West by 63 Degrees North

The Grid Geographic Flag for the tallest point in all of the United States of America uses the colours: red, blue, indigo, yellow, and black.  The tribar represents longitude while the stars represent latitude.  The colours are coded to a number, which is based upon the order of the rainbow.

Since red is the first colour of the official rainbow, it represents 1.  Likewise blue is the fifth colour, that represents 5.  Thus the tribar represents 151.  Likewise Mt. Denali rests on 151th West.  Additionally the central white pentagon indicates this is a Western Meridian, otherwise if it were yellow it would indicate an Eastern Meridian.

Since indigo is the sixth colour, it represents 6.  Finally as yellow is third colour, it represents 3.  Thus 63 is the latitude.  Its northern parallel is indicated since the dominant star points upwards.  Thus if the dominant star were pointing down, it

would indicate a southern parallel.

Note this mountain's middle name is Mt. McKinley and stands at 6190 Meters above sea level.

image credit: Wikipedia
https://en.wikipedia.org/wiki/Denali#/media/File:Wonder_Lake_and_Denali.jpg

Flag for the Western most point of the United States at 124 Degrees West by 48 Degrees North: Cape Alava, Washington State

The most western point of the United 48 States of the USA is in Washington State.  This is non-political truly scientific flag that has the colours ordered to numbers.  The numbers themselves represent latitude and longitude.  In this case red is 1, since it is the first colour in the rainbow.  Orange is 2, as it is the second colour of the rainbow, while green is 4, you guessed it, as it is the 4th colour of the official rainbow.  Thus 124 represents the longitude.  The white pentagon represents the Western Hemisphere, otherwise it'd be yellow for the Eastern Hemisphere.

The stars represents lines of latitude. In this case it is 48.  As the dominant star is pointing upwards, it indicates the Northern Hemisphere.

image credit: Wikipedia
https://en.wikipedia.org/wiki/Cape_Alava#/media/File:Cape_Alava_Ozette_Island.jpg

West Quoddy Head, Maine - 66 Degrees West by 44 Degrees North

The most eastern point in the USA United 48 is at West Quoddy Head, Maine.  Its longitude and latitude are 66 Degrees West by 44 Degrees North.  The colours are coded to numbers as ordered by the rainbow.  Since indigo is the 6th colour of the rainbow it appears twice as double.  Likewise green is the 4th colours of the rainbow and 44 makes two green stars.  Please see the key below.  Note these types of flags are scientifically objective.  True blue blooded vexillological flags.

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image credit Wikipedia: https://en.wikipedia.org/wiki/West_Quoddy_Head_Light#/media/File:West_Quoddy_Head_Light.jpg

Flag for the Geographic Grid of the Middle Rocks, Disputed Claim by Sigapore and Malaysia

The Middle Rocks are in the Pacific Ocean and a disputed claim between Malaysia and Singapore.  Here is a non-national affiliated flag that represents the geographical area of the space.  The colours are coded to numbers as set by the rainbow.  Red is 1 and the 1st colour of the rainbow.  Green is 4 as is the 4th colour of the rainbow, while white represents 0, since it is not a part of the official rainbow.  Thus the colours red, white, green read as 104 East.  The East designation is discerned by the central yellow pentagon, otherwise a central white pentagon represents a Western line of longitude.

The stars indicate latitude.  Here it is 01 degrees.  The dominant star is white, while the lesser star is red.  This translates to 01 North.  It is North because the dominant star is pointing upwards, otherwise it'd be South.  Capeesh?

Flag for 49 Degrees East by 45 Degrees North: Ukatny Island in the Caspian Sea

Ukatny Island is a disputed place in the Caspian Sea, between Russia and Khazaktan.  Here the tribar is coded to longitude, while the stars are coded to latitude.  The tribar reads as white, green, pink which matches up to 049.  As the tribar makes vertical lines it makes sense to have it represent the longitude, which is 049 degrees.  The yellow pentagon represents the Eastern Hemisphere, otherwise it'd be white for the Western Hemisphere. 

The dominant upward star indicates it is in the Northern Hemisphere.  The dominant green star represents the 10s portion of latitude, while the lesser five pointed star represents the 1s portion of the latitude: thus green, blue represents 4,5.  Because green is the 4th color of the rainbow, while blue is the 5th color of the rainbow.

Flag for 89 Degrees West by 39 Degrees North: Springfield, Illions Geographic Flag

Springfield, Illinois can fly this flag because it is a part of the 89W by 89N.  The tribar is coded to the longitude, while the stars are color coded to the latitude.