Which is the best example of a primary source document useful in the study of history?

Look at the map of cities in the united states at the turn of the twentish century what impact did railroads have on cities across the united states at the turn of the twentish century

As the tide of the seven years’ war (french and indian war) turned in britain’s favor, the iroquois

How did the theory of social darwinism impact immigrants? it inspired in the immigrants pride that they were able to survive the harsh conditions of their home countries to come to the united states. it demonstrated that immigrants were the most suitable candidates for factory work because they were the most likely to immigrate to rural areas. it encouraged assimilation of immigrants into the american culture through education that involved courses in english and american food and clothing. it provided new american immigrants with a clearly defined social support system to ensure that basic nutritional, educational, employment, and health care needs were met.