Why did congress impose a national speed limit of 55 miles per hour in the 1970s?

Which of the following resulted from the passage of the dawes act in 1887?

Over time, who did the nature of slavery change in america

What is the main difference between primary and secondary sources? a. primary sources are historical documents, and secondary sources are modern-day documents. b. primary sources are derived from museums and archives, and secondary sources are created by history students and academics. c. primary sources are found in ancient places with a rich history, and secondary sources are found in historical journals and blogs. d. primary sources are created during a particular historical era, and secondary sources are created by studying primary sources.