By the 1740s it was clear that Skrælige was not going to stop growing in population anytime soon. Rather than have the towns continue a somewhat haphazard pattern of growth, the Þing determined that each town should devise a street plan to accommodate future growth. The specifics of each plan were left up to the town, however. The amount of planning varied - for instance, Ragnarsson's plan was a very loose guideline, and Havant expanded its rigid grid pattern.
The most interesting plan, however, was for Skrælingborough. Taking inspiration from the Oglethorpe Plan in the recently settled Savannah, Georgia, Member of the Þing (MÞ) Þorormur Goðason devised a plan (later known as the Þorormur Plan) that divided up the area around the city walls into seven wards. Five of these sections had a small open space in the middle for the public to use. The second section was not sufficiently big enough for its own public space, but the whole sixth section was designated as a common space for the whole town.
The seven sections were named, in clockwise order:
Mikjall Square (Mikjallstorg), named for Mikjáll Freydisson
Abenaki Ward (Abenakideild)
Christian Square (Christianstorg), named for the Danish King Christian IV
Christina Park (Christinagarður), named for the Swedish Queen Christina
Stuyvesant Place (Stuyvesanttorg), named for the New Netherlands Director-General
Skrælingborough Common
Charles Ward (Karlsdeild), named for King Charles II of England
Wars continued on-and-off with the French and their Native American allies in the nearby areas of the continent. King George's War (1744-48, part of the War of the Austrian Succession) did not directly impact Skrælige, but the war killed almost 10% of the adult male population of Massachusetts Bay. Estimates show a loss of around 5% of Skrælige's adult male population, as many were recruited into the war effort. Quickly following this conflict - well, continuing it - was Father Le Loutre's War (1749-55) fought in Nova Scotia and Acadia. This war began due to the English establishing Halifax, in direct violation of their previous treaties with the Mi'kmaq. And then there was the biggest one, the French and Indian War (1754-63), part of the Seven Years' War.
The French and Indian War began as a conflict in the Ohio Country, and became a war when militiamen led by a 22-year old named George Washington ambushed a French patrol. By 1760, the British had taken over all of Acadia, expelled most of the Acadians in an act that can debatably be called genocidal, and forced the negotiated capitulation of Montreal and Quebec. This was formalized in the Treaty of Paris (1763), granting all French North American territory east of the Mississippi River* to Great Britain. (Land west of the Mississippi had been granted to Spain the previous year.) Florida (both East and West) was transferred from Spain to Britain as well. Britain also gained a lot of debt, nearly doubling it in the course of funding the Seven Years' War. Efforts to pay off this debt through increased colonial taxation would become one of the causes of the American Revolution (see below).
*Apart from St. Pierre and Miquelon, which remains part of France to this day.With the expansion of the towns, there was also need for a permanent bridge across the Siguan River. The width of the river, as well as its busy mercantile traffic, meant building a bridge was not previously worth the investment. Frequent ferry services operated from every town on the river, which weren't too inconvenient to use. With more people immigrating though, river traffic became busier, with cross-river traffic interfering with downstream traffic. While a bridge crossing would be difficult to build, it was becoming justified.
There were two main locations considered for the bridge: a crossing from just outside the Skrælingborough to Northstead (about 384m), or a crossing from Middleton to the outskirts of Havant (272m). The Skrælingborough-Northstead option would be the most convenient, connecting the largest town on the north side to the capital. The main drawback would be the interruption to shipping upstream, as a bridge would block the largest ships from sailing up to Middleton. The Middleton-Havant option was 4.3km from the capital, but wouldn't block shipping traffic, as large ocean-going vessels didn't ever go much further upstream anyway.
Most people in Skrælingborough preferred the first option, but the leaders of Middleton wanted the bridge directly connecting to them. By emphasizing the significant cost and engineering challenge to the government in Boston, Middleton convinced them to approve the second option in 1753. Work began on a large quarry up the South Stream (the other river in Middleton that forks off of the Siguan) to dig up stone for the bridge, as well as provide domestic building supplies for the expanding towns.
The Middleton Quarry, begun in 1753.
Bridge construction progress as of 1764.
However, the outbreak of the French and Indian War severely cut back construction efforts on the bridge itself. Construction resumed in the 1760s, although significant debts meant that it would only be completed in 1769.
Newhope, population 1,197 as of 1764
Ragnarsson, pop. 241
Northstead, pop. 867
New Jorvik (part of Skrælingborough), pop. 250
Havant, pop. 471
Abenakiborough, pop. 249
By 1764, Massachusetts caved into the constant demands of the colonial governor and British authorities to perform a census. All of Skrælige's counts were completed by the end of 1764, though reluctant towns on the mainland were still resistant. They had to be pressured by the threat of fines to comply by May 25th, 1765.
The results of the count within Skrælig County in 1764 were:
Abenakiborough: 249 (+163)
Copperstein: 209 (+10)
Havant: 471 (+240)
Middleton: 817 (+469)
Newhope: 1,197 (+517)
Main Town: 1,115 (+531)
Stefnabjarg: 82 (-14)
Northstead: 867 (+345)
Main Town: 865 (+343)
Vitathorpe: 2
Ragnarsson: 241 (+128)
Skrælingborough: 3,897 (+1985)
Central Area: 3,647 (+1882)
New Jorvik: 250 (+103)
Atlantica: 39
Bradstreet: 116 (+84)
Egilstead: 317 (+201)
Fjallvik: 56
Freydiston: 63 (+24)
Littlevik: 255 (+98)
Middlesun: 158 (+69)
Northbay: 71 (+50)
Northney: 92 (+49)
Raskrom: 304 (+182)
Southfall: 47 (+33)
Southreyn: 31 (+9)
Thorfall: 89 (+54)
Total: 9,586 (+4645)
The population of the islands had roughly doubled since the 1740 census. This was the most significant growth in the islands' history, and was showing no signs of stopping. The population was still small compared to the mainland though: Maine counted 23,993 people, and the rest of Massachusetts counted 215,718 people.
Settlement of the remaining "unsettled" lands continued, and by 1769 every part of the Skræligen Islands was associated with an incorporated town. In 1747 Fjallvik was founded on a sheltered bay on the northeastern part of Storreyn. Five years later in 1752, Atlantica was settled midway between Thorfall and Fjallvik. Later infrastructure improvements would create the Atlantic Road, connecting Littlevik (also the southern end of the Almannavegr) to Fjallvik along the Atlantic coast. New roads crossed the mountain passes from the Atlantic settlements to the Siguan River Valley.
To the north, Burnet (1768) and Northsound (1769) filled in the map. Burnet was built north of Ragnarsson, and Northsound was built along the channel between Storreyn and Northney. This was now the northernmost point of the Almannavegr, and indirectly connected to Northney via boat.
After the heavy British involvement in the French and Indian War, the British government became much more involved with colonial affairs. The huge debts from the war (both in North America and Europe) required new taxation to pay for it - at least, according to the British authorities. Many in the colonies argued that they already paid their fair share - after all, their troops were involved alongside the British regulars. The first acts to directly tax the colonists came with the Sugar Act of 1764 and the Stamp Act of 1765. These were unsuccessful in gathering revenue, but were very successful in uniting the colonies against the British Parliament. Prior to these acts, all taxation was done by the colonial governments, meaning that most citizens (i.e. land-owning men) had representation. This time the British Parliament stepped in, asserting authority that it had not previously used. This was the source of the saying "No taxation without representation", as the colonists had no representation in Westminster - only land-owning men in Britain could vote. (It's worth noting here that the proportion of land owners was far lower in Britain - most men owned land in the colonies, but this was very much not the case in Britain.) Violent revolts took place over the new taxes, and were significant enough to convince an already-divided Parliament to repeal them in 1766.
Parliament still claimed the right to tax the colonies directly, however, and tried again with the Townshend Acts in 1767 and 68. Revolts began again, including attacks on customs officials, but this time the British government reacted by putting Boston under military occupation. This soon led to the Boston Massacre in 1770 and the Boston Tea Party in 1773, which in turn led to the punitive Coercive Acts in 1774 (known as the Intolerable Acts in the colonies). These included shutting the port of Boston and unilaterally terminating the provincial assembly. Instead, the members met in Concord, forming the Massachusetts Provincial Congress. This meant that the British government under Governor Thomas Gage only de facto controlled Charlestown, Boston, and central Skrælige around Ft. Charles, where British troops were stationed.
This further escalated into open rebellion with the Battles of Lexington and Concord on April 19th, 1775.
The 10% adult male casualty figure comes from Wikipedia, where there is a "citation needed" footnote, so... take this one with a grain of salt.
More about Colonial American Censuses: https://www.census.gov/history/pdf/colonialbostonpops.pdf