This voided the missouri compromise and removed the 36* 30' line.

Compromise of 1850

The Compromise of 1850 was a new compromise to deal with slavery and new lands acquired by the Mexican American War.

The Compromise of 1850 allowed California to enter the Union as a free state despite being under the 36,30 line. The compromise included the passage of the Fugitive Slave Act making it a requirement to return runaway slaves to owners regardless if they make it to a free state. Territories would be allowed to vote for the status as a free or slave territory. The compromise also included the ending of the slave trade in Washington DC.

a historian researching the immigration policies of the early 1900s would expect a source written today,rather than in 1910 to :

( a ) be more interested in objective data and statistics.