West Virginia Three-Digit State Routes

How do three-digit routes in West Virginia get their numbers? To be truthful, I have no idea, as there is no rhyme or reason to the way three-digit numbers are assigned. I do have a few theories, however.
Some numbers, such as 259 and 311, appear to be continuations of routes from other states. Others get numbers based on the numbers they used to have before new highways were built. For instance, the former route of US 52 south of Huntington is now WV 152. And when WV 48 was renumbered when US 48 was built, it became WV 480.
But I think many of the roads that have three-digit numbers were former county roads that have been accepted into the state system. My reason for thinking this is an understanding of the way county roads are numbered in West Virginia. Many of them are numbered based on the main roads in the area. For instance, a highway which branches off of US 52 might be numbered and signed thus:

This is one of the famous West Virginia "fractional routes." Below is an actual photo of one of these signs, along US 52 in Wayne County:

This sign is located on WV 62 near Charleston:

Say the highway 52/1 in my homemade example above later becomes a state route. It might get the number WV 521. Examples of this type of numbering might be WV 622, which is located near WV 62; and WV 211, which is near the former US 21. If anyone has any better theories, I'd love to hear them.

Route	Starting Point (West or South)	Ending Point (East or North)	Counties	Notes
WV 100	US 19, Monongalia	US 19, Monongalia	Monongalia
WV 101	US 60, Cabell	US 60, Cabell	Cabell	Old two-mile section of US 60. Not signed. A part of Eighth Avenue and 29th Street West in Huntington.
WV 102	Virginia State Line, Mercer	Virginia State Line, Mercer	Mercer	Apparently a continuation of VA 102. Does not intersect any other West Virginia state highway.
WV 103	WV 161, McDowell	US 52/WV 16, McDowell	McDowell
WV 104	US 19, Mercer	US 460, Mercer	Mercer	Part of this route is old US 460.
WV 105	WV 2, Hancock	US 22, Brooke	Hancock, Brooke	Pennsylvania Avenue and Colliers Way in Weirton.
WV 106	US 60, Cabell	Ohio State Line, Cabell	Cabell	Huntington's East End Bridge. Route number is not signed.
WV 107	WV 3, Summers	WV 20, Summers	Summers	Located in Hinton.
WV 112	US 19, Mercer	US 460, Mercer	Mercer	Originally signed as WV 12, when WV 12 followed US 219 and US 460 into Giles County, Va., and back into West Virginia.
WV 114	US 60, Kanawha	I-79, Kanawha	Kanawha	Old WV 14.
WV 115	US 340, Jefferson	WV 9, Jefferson	Jefferson	Old WV 9 through Ranson and Charles Town. Route not signed.
WV 122	WV 12, Summers	US 219, Monroe	Summers, Monroe
WV 123	Virginia State Line, Mercer	US 19/460, Mercer	Mercer
WV 125	???	???	Raleigh, Summers	This route does not yet exist, but the route number is reserved for the proposed New River Parkway (according to WVDOT).
WV 127	WV 29, Hampshire	Virginia State Line, Hampshire	Hampshire	Apparently a continuation of VA 127.
WV 129	WV 39, Nicholas	WV 41, Nicholas	Nicholas
WV 131	US 19, Harrison	US 50, Harrison	Harrison	Former route of old WV 73 (County Route 73/73) and County Route 13. (Info courtesy Michael Miller of Charleston, W. Va.)
WV 150	WV 55, Pocahontas	WV 219/WV 55, Pocahontas	Pocahontas	Highland Scenic Byway.
WV 152	US 52, Wayne	I-64/WV 527, Cabell	Wayne, Cabell	Former route of US 52. Becomes WV 527 at the I-64 interchange.
WV 161	WV 16, McDowell	US 52, McDowell	McDowell
WV 180	WV 18, Tyler	WV 2, Wetzel	Tyler, Wetzel
WV 210	US 19, Raleigh	WV 16, Raleigh	Raleigh	Kanawha Street in Beckley.
WV 211	WV 16, Fayette	WV 16/61, Fayette	Fayette	Located in Mt. Hope. Old alignment of US 21.
WV 214	WV 3, Lincoln	US 119/WV 601, Kanawha	Lincoln, Kanawha	Old WV 14. Route is not signed in its entirety; only from WV 3 to US 119 in Lincoln County. Route is not signed from US 119 intersection to South Charleston.
WV 218	US 19, Marion	Pennsylvania State Line, Monongalia	Marion, Monongalia	Appears to be a continuation of PA 218.
WV 230	US 340, Jefferson	WV 480, Jefferson	Jefferson
WV 251	WV 2, Ohio	South Front Street, Ohio	Ohio	Bridge between downtown Wheeling and Ohio River island; may have been a part of US 40 and/or US 250 at one time. Historic Wheeling Suspension Bridge designed by John Roebling. Route not signed.
WV 252	North Huron Street, Ohio	Ohio State Line, Ohio	Ohio	Bridge between Ohio River island at Wheeling and Ohio; may have been a part of US 40 and/or US 250 at one time. Route not signed.
WV 259	Virginia State Line, Hardy	Virginia State Line, Hampshire	Hardy, Hampshire	Appears to be a continuation of VA 259.
WV 270	US 19, Harrison	I-79, Harrison	Harrison	New state route. Formerly County Route 27.
WV 305	WV 97, Raleigh	WV 3, Raleigh	Raleigh
WV 307	US 19, Raleigh	US 19, Raleigh	Raleigh	This route serves Little Beaver State Park.
WV 310	US 50, Taylor	US 250, Marion	Taylor, Marion
WV 311 (North Section)	Virginia State Line, Greenbrier	I-64/US 60, Greenbrier	Greenbrier	Appears to be a continuation of VA 311. Possibly a very old former alignment of US 311.
WV 311 (South Section)	Virginia State Line, Monroe	Virginia State Line, Monroe	Monroe	Appears to be a continuation of VA 311. Possibly a very old former alignment of US 311.
WV 331	US 33/WV 2, Jackson	US 33, Jackson	Jackson
WV 338	WV 68, Jackson	Ohio State Line, Jackson	Jackson	Bridge crossing Ohio River at Ravenswood, connecting WV 68 with OH 124 and OH 338.
WV 480	WV 9, Jefferson	Maryland State Line, Jefferson	Jefferson	This route was WV 48 until US 48 was opened in the 1970s.
WV 527	I-64/WV 152, Cabell	Ohio State Line, Cabell	Cabell	Former route of US 52. A continuation of OH 527, although an extension of WV 152 would have worked just as well.
WV 501	WV 62, Kanawha	WV 622, Kanawha	Kanawha
WV 598	Virginia State Line, Mercer	US 52, Mercer	Mercer	Former route of US 52 (and also US 21). Apparently a continuation of VA 598.
WV 601	US 119/WV 214, Kanawha	US 60, Kanawha	Kanawha
WV 612	I-64/I-77, Fayette	US 19, Fayette	Fayette
WV 622	WV 25, Kanawha	I-77, Kanawha	Kanawha
WV 635	Virginia State Line, McDowell	WV 83, McDowell	McDowell	Probably a continuation of VA Secondary Route 635.
WV 705	US 19/WV 7, Monongalia	US 119, Monongalia	Monongalia
WV 807	Ohio State Line, Pleasants	WV 2, Pleasants	Pleasants	Bridge over Ohio River at St. Marys. Route not signed. Possibly a continuation of OH 807.
WV 869	US 35, Putnam	WV 62, Putnam	Putnam	Bridge over Kanawha River
WV 891	US 250, Marshall	Pennsylvania State Line, Marshall	Marshall
WV 892	WV 68, Wood	WV 68, Wood	Wood
WV 901	WV 9, Berkeley	US 11, Berkeley	Berkeley
WV 956	WV 28, Mineral	Maryland State Line, Mineral	Mineral
WV 971	WV 97, Wyoming	WV 10, Wyoming	Wyoming
WV 972	US 50, Mineral	US 220, Mineral	Mineral