Answer to Question 1
The construction of the transcontinental railroads made transportation of settlers into the Great Plains much easier, but, more importantly, these railroads provided improved transportation of farm products to faraway markets.
Answer to Question 2
The humid continental climate of the region is highly variable, with drought periods and heavy rainfall in other periods. This is a region where warm and cold air masses frequently meet, creating strong storm systems. Warm air masses from the Pacific and Gulf of Mexico are drawn into the region and sometimes meet up with cold air masses pulled southward from the Arctic.