Industrialization
Along with the population and political
environment of Israel, the economic base of Tel Aviv transformed over time.
Jaffa, at the time of Tel Aviv's inception, was a citrus-growing and export
town. The natural harbor and fertile growing conditions
surrounding the town helped these industries remain the staples of the small
and stable town. However, following the founding of Tel Aviv, the economy
of the area began to change.
At first, Zionist settlers in Tel Aviv worked in Jaffa and lived in the settlement. As the population increased, landowners in Jaffa found there was great opportunity in selling land to arriving immigrants (often for more than it was worth). And Jews already living in the settlement found opportunities in construction. For over a decade, Tel Aviv's economy was based completely on construction, land speculation and the commute to Jaffa. However, in 1921, violent clashes between Arabs and Jews led the two cities of Tel Aviv and Jaffa to cut all ties to one another. Tel Aviv's economy started to develop independent of Jaffa.
Into the 1920's, new waves of immigration brought capital from Europe as well as new industries. Skilled craftsmen from Eastern Europe brought their businesses with them and continued to export goods. The usual base of the area was citrus growth, but in order to facilitate residential growth, much of the groundwater under Tel Aviv had been drained. Hence, the city was not able to develop agriculture as a base.
As time went on, more light industries from Europe continued to pop up
in Tel Aviv. Unable to cooperate with Jaffa, the only thing the growing
city lacked was a port of its own. Since the city had slowly been expanding
north toward the Yarqon River, a port was constructed at its mouth in the
early 1940's. The biggest goal of this development was to attract industry
further up the coast, away from Jaffa. 
In essence, the port of Tel Aviv failed. First of all, by the time the port was built, roadways and trucks were already becoming important modes of transportation. And since the northern city of Haifa had a well-established, functional port, industries in Tel Aviv tended to rely on Haifa for shipping. Thus, the road system developed to cater to industries in Tel Aviv - with major corridors running to Haifa and Jerusalem.
Today, Tel Aviv harbors a number of economic functions. Industry is mostly light and high-tech, concentrating in electronics, chemicals, food processing, pharmaceutics and textiles. Also in Tel Aviv are the Israeli Stock Exchange and numerous business and agricultural headquarters.