In the 1720s, news datelined London appeared in colonial newspapers on average 162 days later

From Independence: The Tangled Roots of The American Revolution by Thomas P. Slaughter.

I have an interest in the role that reading plays in economic development. Specifically, it is clear that there is a correlation between increasingly productive and complex economies and increased reading. But is there a causative relationship (and if so, in which direction) or is the correlation due to some independent third variable?

Slaughter doesn't answer that question, but relays interesting information. From page 39.

In the first half of the eighteenth century, the time required for overland travel from London to Edinburgh declined by 40 percent; over the same period, clearances of ships in colonial ports doubled, and schedules became more regular and thus predictable. The transatlantic voyage was also becoming shorter. In the second decade of the eighteenth century, news datelined London appeared in colonial newspapers on average 162 days later; by 1730, the year of Whitefield's arrival, the lag was about half that, 83 days.

In 1700, colonial America had no newspaper, but there were eleven by the time Whitefield arrived. Over that same forty years, the number of printing shops in Boston doubled. In New York, twenty-two different newspapers were published between 1725 and 1776. There were four printing shops in the city by 1742, five in 1750, six in 1762, and twelve by the 1770s. The average number of books published annually in New York rose from twenty in the 1730s to twenty-five in the 1740s, thirty-two in the 1750s, fifty-five in the 1760s and by 1774 there were 155, as the market for everything from political pamphlets to abridged novels to narratives of Indian captivity rose exponentially.