4. Expansion should be like a balloon expanding, what regions (states) do not follow an expansion from east to west? Can you speculate why?

Regarding internal borders, while territories could shift wildly in size, once established states have generally retained their initial borders. Only four states—Maine, Kentucky, Vermont, and West Virginia—have been created from land claimed by another state; all of the others were created from territories or directly from acquisitions. Four states—Louisiana, Missouri, Nevada, and Pennsylvania—have expanded significantly by acquiring additional federal territory after their initial admission to the Union. The last state of the contiguous United States, commonly called the "lower 48", was admitted in 1912; the fiftieth and most recent state was admitted in 1959.

This area today makes up the states of Indiana, Ohio, Michigan, Wisconsin, and Illinois. Daniel Boone led settlers across the Cumberland Gap and into Kentucky. In 1803, President Thomas Jefferson bought the Louisiana Territory from the French for $15 million. The Westward expansion was brought about by the increasing number of population as well as the need to acquire more land to farm and produce crops.

Explanation:

offline recommendation systems option b

because recommendation systems produce a list of two ways

1. through collaborative filtering

or

2. through content-based filtering