Tidewater can be defined by different boundaries, depending upon your point of view.
A geologist may define Tidewater as the area east of the Fall Line, east of the crystalline rocks of the Piedmont. An astronomer may consider Tidewater to be the area where the water level rises and falls each day based on the gravitational pull of the moon (and the sun, too).
An ecologist may start talking about the Chesapeake Bay estuary, or the downstream end of watersheds (including the mouths of the rivers) east of the Fall Line. A historian may consider Tidewater to be the location of early Colonial settlement around the Chesapeake Bay up to the 1730's. (In that case, Alexandria would be not be a Tidewater community, because Alexandria was not chartered until 1749.)
A voice coach might recognize certain accents ("let's go to the riv-ah and catch some fish...") as being associated with Tidewater Virginia. A politician, business owner, or government official in southeastern Virginia may tell you that Tidewater is a region with a complex mix of official jurisdictions; the waterways and history of settlement have fragmented the communities into separate cities/counties.
If you drive down I-64 east of Williamsburg, it's very difficult to identify the boundaries of Newport News, Hampton, Norfolk, and Virginia Beach. You may see the signs to Poquoson... but how do you know you've reached it?
If you head west from Virginia Beach, the edges of the political jurisdictions of Norfolk, Portsmouth, and Chesapeake are no more obvious than what you saw driving east. The region's political boundaries resemble Los Angeles, with separate urbanized jurisdictions adjacent to each other and little undeveloped farmland separating the cities. The city lines blur in a sea of monotonous urban development - except for the Eastern Shore. That area is still undeveloped at the moment, though a reduced toll on the Chesapeake Bay-Bridge Tunnel may encourage more commuters to live in Northampton County.
When Tidewater Virginia is defined as a cultural region, the boundaries lack scientific precision. Some people consider the Eastern Shore, the Northern Neck, the Middle Peninsula, the Peninsula, and the portion of Hampton Roads south of the James River to be "Tidewater." Others think "Hampton Roads" and "Tidewater" are the same, excluding the Eastern Shore.
Some consider Tidewater to be just the portion of Virginia that is:
1) east of the Fall Line, and
2) between the James and Potomac rivers, and
3) west of the Chesapeake Bay
That definition would exclude the Eastern Shore, as well as Virginia Beach, Norfolk, Portsmouth, and other jurisdictions south of the James River. You may hear people discuss "Tidewater and Hampton Roads," to include specifically the Chesapeake Bay watershed south of the James River.
All definitions are correct - and all definitions are wrong. Cultural regions are defined in different ways by different people, and there is no official judge sitting in big chair at the front of an International Court of Regional Boundaries to make "official" decisions.
What's missing? The cities of Manassas and Manassas Park, the counties of Loudoun and Fauquier - and other jurisdictions in the Piedmont, Blue Ridge, and Valley and Ridge provinces, where the rivers drain into the Chesapeake Bay but the water levels are not affected by tides.
necks in York County (Back Creek)
Source: National Atlas
Even defining the edge of Hampton Roads can stimulate a geography debate. The Hampton Roads community is split into two major components, as represented by the location of the regional airports - one on the Peninsula at Newport News-Williamsburg, and one in Norfolk. If someone south of the James River says they are going to the airport, you can generally assume that they are going to the Norfolk International Airport. Someone living north of the James River will probably use the Newport News-Williamsburg or Richmond airports, avoiding the traffic delays at the Hampton Roads Bridge-Tunnel.
The airports in Newport News-Williamsburg and Richmond are growing as the population in Hampton Roads increases. However, so long as the region has three small airports, Hampton Roads is unlikely to attract a carrier to offer nonstop flights to Europe. Southeast Virginia residents will have to keep going to Dulles or Raleigh-Durham airports to fly direct to London; the "international" in the names of southeast Virginia airports reflects the ability to reach other countries after stopping at another airport.
Another clue to the impact of the waterways fragmenting the population - there is no culturally-unifying professional sports team in the region. Back in 2000, one source described the problem as follows: "Poor Norfolk-Virginia Beach-Newport News, VA-NC, it's the largest metropolitan area (ranked 27th with a population of 1,542,143) in the U.S. without any professional sports teams in the four leagues. It's home to 500,000 more people than #45 Jacksonville yet it still lacks a team of its own."2
Kingsmill and other retirement communities around Williamsburg are adding suburban growth to the already-urbanized areas at the southeastern tip the Peninsula (the land between the York and James rivers)
Source: ESRI, ArcGIS Online
Tidewater and Shipping
Virginia's first colonists nearly starved to death, but soon after the winter of 1609-10 the colony became self-sufficient in food production. The first center of colonial agriculture was on the Peninsula and south of the James River.
The early colonists living south of the James River in southeastern Virginia raised wheat and made bread, using windmills to power the grindstones that converted the wheat into flour. They also raised hogs and cattle for sale to ship captains. The livestock yielded fresh meat that could be preserved with salt imported from Bermuda, the Bahamas, or nearby Caribbean islands.
In the 1600's and 1700's, Virginia farmers exported meat to Caribbean islands that were using their land to grow sugar cane (and thus needed to import food for the slaves and other residents of the islands). In what is now the City of Virginia Beach, islands in Back Bay and "necks" between tidal creeks in Lynnhaven Bay were used as pastures. Because water surrounded three sides of the necks, the labor and materials to build fences to enclose pastures were minimized. Even today, south of the "Green Line" that defines land use patterns, a substantial portion of the City of Virginia Beach is still productive farmland.
The pattern of rivers and "necks" of land throughout Tidewater shaped the settlement of the region by Europeans. The English considered the rivers and Chesapeake Bay to be a transportation bonus, not a barrier to travel. Ships that crossed the Atlantic Ocean from Europe - and later, Africa - could sail far up the bay and its tributaries, using the deep river channels to reach as far west as the Fall Line (modern Interstate 95).
In the 1730's, laws required Virginia tobacco to be inspected for quality before export were finally implemented, and only then did "tobacco towns" finally develop across Tidewater. Large planters relied upon agents in London to handle sales of their tobacco, then purchase requested items in England and ship them back to Virginia. Smaller tobacco farmers grew to rely upon Scottish merchants who set up stores in small communities such as Dumfries. Those merchants paid for tobacco before it was shipped across the Atlantic Ocean, and the farmers could purchase cloth, furniture, china, glassware, and other manufactured items in that same store.3
In colonial times, there was a direct connection between ports in Europe and the wharves of individual plantations on various peninsulas or "necks" of land in eastern Virginia. The physical geography affected the cultural pattern - large plantation owners saw no value in establishing towns where European goods could be delivered, stored, and sold, when ocean-going ships could transport manufactured products from England directly to each plantation and then load a return cargo of hogsheads of tobacco. Development of towns in Virginia was delayed until the population finally moved inland, away from the easy transportation offered by so many peninsulas of land in Tidewater Virginia.
In 1730, over a century after Jamestown was founded, Governor Gooch was able to get the General Assembly to mandate establishment of tobacco inspection warehouses. Scottish merchants started stores near the warehouses, providing small farmers an alternative to dealing with large plantation owners when buying European goods/selling tobacco. The warehouses and stores became the nucleus for many early Tidewater towns, such as Alexandria and Occoquan.
Though Jamestown was the first town created by Europeans in Virginia and Hampton was settled next, Norfolk has been the state's primary port since the 1700's. Norfolk's harbor at the mouth of the Elizabeth River was naturally deep, sheltered from storms, and close to the Atlantic Ocean. By doing business at Norfolk, ship captains could avoid a tedious journey of sailing up the James River, tacking back and forth to stay in the narrow channel.
The loyalty of the white residents in Norfolk/Portsmouth to the "mother country" during the American Revolution was affected by the close economic ties to London and Glasgow. In April, 1775, Lord Dunmore (the last colonial governor) fled Williamsburg. He chose Norfolk as his primary base of resistance against the rebels, but was forced to abandon it after the Virginians burnt the town at the start of 1776. (The British completed the burning of the town, and that was added to the list of "outrages" justifying the American Revolution. It took over 100 years before the true role of the local Virginia rebels in torching their largest city was exposed...)4
Today, the the Hampton Roads region still depends upon the Chesapeake Bay as its primary economic resource. Now, however, the region is taking advantage of deep river channels and protected harbors for military shipping, as well as export of agricultural goods and coal to Europe annd import of manufactured products from Asia. The US Navy is the main employer in Hampton Roads. The Norfolk Navy Yard has been the primary economic stimulus for expansion in the area, affecting growth north of the James River as well as south. The growth led to Tidewater being the first Virginia region to support commercial broadcasting.5