Seattle was the gateway from the lower 48 to the Klondike Gold Rush. Most miners bought their supplies in Seattle then took a ship from there to Skagway or Dyea.
Skagway was a main port in the gold rush. People would stop there and stock up on supplies before heading up the White Pass trail to Dawson. Skagway had problems with theives and gangs of robbers. One of the most famous theives was Soapy Smith.
This is a picture of Skagway during the Gold Rush
Dyea was the beginning of the Chilkoot Trail. Most people chose Dyea instead of Skagway because there was a man in Skagway named Soapy Smith who was a thief. Miners didn't want to have their equipment and gold stolen. Dyea had shops where miners would buy last minute supplies before heading up the Chilkoot trail.
Dawson was the last stop in the Klondike Gold Rush. When miners got to Dawson they would stake a claim and start mining for gold. If they didn't find any at that particular claim they would stake another claim and start again. If they happened to find any gold they would keep on mining until winter came. Some miners would go back to the lower 48 and some might stay through the winter in Dawson.
Picture of Dawson City from the Yukon River in 1994