[226] Dallas, although from protectionist Pennsylvania, voted for the bill, having decided his best political prospects lay in supporting the administration.[227] Polk signed the Walker Tariff into law, substantially reducing the rates that had been set by the Tariff of 1842.[228] The reduction of tariffs in the United States and the repeal of the Corn Laws in Great Britain led to a boom in Anglo-American trade.[224]

Development of the country[edit]
Congress passed the Rivers and Harbors Bill in 1846 to provide $500,000 to improve port facilities, but Polk vetoed it. Polk believed that the bill was unconstitutional because it unfairly favored particular areas, including ports that had no foreign trade. Polk considered internal improvements to be matters for the states, and feared that passing the bill would encourage legislators to compete for favors for their home district—a type of corruption that he felt would spell doom to the virtue of the republic.[229] In this regard he followed his hero Jackson, who had vetoed the Maysville Road Bill in 1830 on similar grounds.[230]
Opposed by conviction to Federal funding for internal improvements, Polk stood strongly against all such bills.