What made a number of the Mayflower settlers unique? How is it improbable that their story has come to define the mythological origins of American culture?

The correct answer to this open question is the following.

What made a number of the Mayflower settlers unique was the fact that they had to agree on a new form of government for the future colony to be established in the Americas. It was known as the Mayflower Compact. This set of rules was agreed upon while Pilgrims were traveling in the Mayflower ship to North America. That agreement served as the first set of rules to apply in the Cape Cod colony, in Massachusetts.  

It is improbable that their story has come to define the mythological origins of American culture in that indeed they celebrated one version of what today is known as Thanksgiving, the most important holiday in the United States. However, historians think that the fest was celebrated just one time in 1621 and was not repeated and did not start a tradition.

the berlin blockade was an international crisis that arose from an attempt by the soviet union, in 1948–49, to force the western allied powers (the united states, the united kingdom, and france) to abandon their post-world war ii jurisdictions in west berlin. in march 1948 the allied powers decided to unite their different occupation zones of germany into a single economic unit. in protest, the soviet representative withdrew from the allied control council. coincident with the introduction of a new deutsche mark in west berlin (as throughout west germany), which the soviets regarded as a violation of agreements with the allies, the soviet occupation forces in eastern germany began a blockade of all rail, road, and water communications between berlin and the west. on june 24 the soviets announced that the four-power administration of berlin had ceased and that the allies no longer had any rights there.