I was surprised to learn that Polk is widely considered one of the most influential presidents of all time, but after reading this book I understood why.
Here's the platform he campaigned on:
1) Lower Tariff's
2) Restructure National Banking System
3) Take California from Mexico through peaceful or other means
4) Secure Oregon Territory and border with Canada/British
Polk promised all these things during his campaign, and unlike the vague and unachievable campaign promises of today, he put his credibility on the line and actually did them in the one term of office he served.
He kick started the industrial revolution by lowering Tariffs for manufacturers, averted financial disaster by restructuring his mentor Andrew Jackson's broken banking system. He stretched the borders of the United States from the Atlantic to the Pacific ocean, securing California which would eventually become one of the largest economies in the world in its own right. Oh yeah, and he averted what would have been a costly drawn out war with Great Britain through tough but fair negotiations.