Its early design took the form of a turbofan-powered stretch of the existing turboprop-powered EMB 120 Brasilia regional aircraft.

While retaining the three-abreast seating of the Brasilia, the twinjet featured a new swept wing and is powered by two rear-fuselage-mounted Rolls-Royce AE 3007 turbofans for a range up to 2,000 nautical miles [nmi] (3,700 km; 2,300 mi).

By the time of its maiden flight on 11 August 1995, Embraer had garnered 18 firm orders, 16 options and 127 letters of intent for the type.

On 10 December 1996, the ERJ 145 received its type certificate; it entered revenue service with ExpressJet Airlines on 6 April 1997.

[4] The jet was anticipated to be able to travel at 400 knots (740 km/h; 460 mph), equipped with the CFE738, Lycoming ALF 502 or Rolls-Royce/Allison AB580 turbofan engines, with the model to be selected in the summer of 1989.

[5] Its supercritical airfoil with a 14% root thickness had its chord extended at the leading edge with a slight sweepback, increased aspect ratio and winglets.

[10] In November 1990, a major reduction in Brazilian government spending, which held 61% of its voting share, resulted in Embraer laying off 32% of its 12,800 employees and suspending development of the EMB 145 for six months.

[11] In March 1991, a revised configuration started wind tunnel testing: the quarter chord wing sweep increased to 22.3° with underslung engines for lower aerodynamic drag.

The semi-monocoque wing has two main and one auxiliary spar and holds 4,500 kg (9,900 lb) of fuel, it has double-slotted fowler flaps and spoilers.

[12] During June 1991, the Brazilian Government loaned $600 million to Embraer and in July the programme was re-evaluated while tooling was 80% complete.

[13] By November 1991, Embraer was still looking for partners to share the risk of the $350 million project, hoping to obtain Government approval by the end of the year.

[13] After re-evaluation late in 1991, the layout was again revised with two rear-fuselage-mounted engines, and a Mach 0.8 cruise speed would be tested in the wind tunnel.

[15] The $14.5 million aircraft is developed with risk-sharing partners including Spain's Gamesa producing the wing; Chile's Enaer for the tail; and the USA's C&D Interiors equipping the cabin.

[15] The standard maximum ramp weight is 19,300 and 20,300 kg (42,500 and 44,800 lb) for the extended-range, it is fitted with Honeywell Primus 1000 integrated avionics.

[15] The estimated $300 million development cost is divided between Embraer for 34%, risksharing partners for 33% (including Belgium's SONACA supplying centre and rear fuselage sections, doors, engine pylons and wing leading-edges), long-term loans from Brazilian development-funding institutions for 23% and participating suppliers for 10%.

Two months later, the discontinuation of the local assembly initiative was announced; it was reported that in excess of 40 ERJ 145 and five Legacy 650s has been completed by this point.

The ERJ140 was designed with fewer seats in order to meet the needs of some major United States airlines, which have an agreement with the pilots' union to limit the number of 50-seat aircraft that can be flown by their affiliates.

[30] The airframe is composed of stretched, machined and chemically milled aluminium, with CFRP for moving parts, GFRP for fairings and sidewalls, kevlar for leading edges and Nomex honeycomb-CFRP/GFRP sandwiches for floors.

[34] Dependent on an individual aircraft's role, overhead bins may be installed; their exclusion gives more headroom but reduces the available storage space for carry-on luggage.

[34] Embraer has stated that every ERJ 145 is capable of being converted into a semi-private aircraft configuration, and that the conversion process can be performed at Embraer-owned service centers.

[33] Numerous aftermarket companies have also offered their own conversions of ERJ family aircraft, often involving various levels of interior refurbishment, such as the installation of an expanded galley, redesigned lavatories, seat track relocation, at-seat power provision, Wi-Fi, alternative ceilings, LED lighting upgrades, and various storage options.

[30] Particular value was attached the American market as there was a near-insatiable hunger for regional aircraft at this time, and thus a substantial amount of potential sales to capitalise upon.

[30] By the 2020s, various operators had elected to retire their ERJ 145 fleets in favour of newer airliners; they have often been replaced by members of Embraer's E-Jet family.

[30][31] To capitalise on the growing sector of corporate/private travellers, some customers have elected to acquire secondhand ERJ145s from regional operators and refurbishing them with new interiors with more luxurious fittings to suit their new role.

[citation needed] By early 2005, 74 ERJ140s had been delivered; while this model has been marketed as ERJ140, its designation on the company's internal documents and on FAA certification is EMB 135KL.

In March 2007, ExpressJet entered into a short-term agreement to operate some regional routes for JetBlue Airways using its ERJ 145 aircraft.

[41] The physical engines are the same (Rolls-Royce AE 3007), however, the FADEC (Full Authority Digital Engine/Electronic Control) logic is what differs between the various models in regards to total thrust capability.