Today has been a second consecutive day of traffic nightmare in Delaware, as the First State copes with the failure of the I-495 Christina River Bridge. While people making short trips to Wilmington or Philadelphia should switch to transit, those relying on the I-95 corridor for longer trips may not have such an easy alternative. For those drivers, I’ve put together this list of recommended alternate routes around the gridlock that is Wilmington. They break down into two broad categories. As a convention, I will assume the direction of travel is towards Philadelphia, and all maps will be clickable links.
The Northern Route: US 1
Coming from Baltimore, DC, or points south, these alternate routes all begin the same way: take I-95 North to Exit 93, the MD-222 Port Deposit exit. Go north on Maryland 222, Maryland 275, and Maryland 276, until you reach US 1 near Rising Sun, MD. Take US 1, the Kennett-Oxford Bypass through Chester County.
From there the best route depends on final destination.
You can take US 1 to US 322 back to I-95 at Chester, for Delaware County’s river towns, South Philadelphia, and South and Southwest Philadelphia including the Airport. That has the drawback of US 322, which bottlenecks and jams frequently as it transitions from four lanes to two, and again at the I-95 merge, which is a left entrance. US 1 itself jams up near Granite Run, but US 1 to I-476 may be a good alternate to US 322.
US 1 itself and Baltimore Pike give access to the heart of Delaware County, including my alma mater’s Sesquicentennial Reunion this weekend. (Fellow Swatties: remember to stash your car at Springfield Mall!)
The Southern Route: I-295/Delaware Memorial Bridge
This is the pricier option, and the slightly riskier one traffic-wise going north, but it’s simpler for those who like simpler directions. It’s also an option for those taking the Eastern Shore Route from DC and Richmond, or going to the Delaware Beaches via Delaware 1. Again, there are multiple branches, which all begin from the same basic route: in Delaware, instead of following I-95 or I-495, follow the Delaware Turnpike/I-295 to the Delaware Memorial Bridge and New Jersey.
For Delaware County and South Philadelphia, follow I-295 north to US 322, the Commodore Barry Bridge. Hop back across the Delaware, and rejoin I-95. The DRPA toll is $5 for northbound drivers; the DRBA toll is $4 for southbound drivers. Philadelphia-bound traffic also retains the option of the Walt Whitman Bridge, but that takes you straight through the construction zone at the Bellmawr interchange. The Commodore Barry route is shorter and safer.
For the River Wards, Northeast Philadelphia, and Bucks County, follow the New Jersey Turnpike north to Exit 4. Take NJ-73 north to the Tacony-Palmyra or Betsy Ross bridges, and if necessary rejoin I-95 there. The New Jersey Turnpike toll in both directions is $2.90 ($2.15 with EZ-Pass off-peak discount), and the Burlington County Bridge Commission toll for northbound drivers is $2.
Sic Transit Philadelphia 
I was pleasantly surprised to discover that the drive to Claymont is in fact fine. There’s an annoying merge down to one lane when you get on 495-S, but that was the case for most of 2010-2011, too, if I recall correctly, although probably for a different reason, so it’s just something to get used to.
According to DelDOT, the backup on I-95 South in the AM rush stretched from Downtown Wilmington to the Pennsylvania State Line. So Claymont is the last point at which the drive is OK. Good argument for parking and taking SEPTA or DART.