Why did workers begin to organize labor unions?

In 1073, the fight over who gets to choose bishops was between pope gregory vii and king henry the iv. t or f

Which best describes the impact of the crusades on european exploration?

How did the construction of the erie canal improve transportation in the united states in the 1820s? a. the canal connected the great lakes to the mississippi river. b. the canal connected the great lakes to the ohio river. c. the canal connected the atlantic and pacific oceans. d. the canal connected the great lakes to the atlantic ocean.